Paper - I MAHESH TUTORIALS S.S.C. Test - III Batch : SB GEOMETRY Chapter : 1, 2 , 6 Date : Q.1. Marks : 30 Time : 1 hr. 15 min. Solve the following : 3 (i) Find the total surface area of a cube with side 1 cm. (ii) If ABC ~ DEF and DEF ~ XYZ and m A = 70º, then find m X. (iii) O is the centre of the circle. If m ABC = 80º, the find m (arc AC) and m (arc ABC). B O C A Q.2. Solve the following : 6 (i) An arc of length 4 cm subtends an angle of measure 40º at the centre. Find the radius and the area of the sector formed by this arc. (ii) In the adjoining figure, AB2 + AC2 = 122, BC = 10. Find the length of the median on side BC. (iii) Q.3. (i) B C Q Curved surface area of a cone with base radius 40 cm is 1640 sq.cm. Find the height of the cone. Solve the following : 9 The curved surface area of a hemisphere is 905 ( = (ii) A 22 ) 7 In the adjoining figure, given two concentric circles of radii 5 and 3, A find the length of a chord of larger circle which touches the smaller one. If BD = 5, find BC. 1 cm2, what is its volume? 7 D O E C B Paper - I ... 2 ... M (iii) In the adjoining figure, LMN = 90º and LKN = 90º, seg MK seg LN. Prove that L R is the midpoint of seg MK. N R K Q.4. (i) Solve the following : 12 A ABCD is cyclic quadrilateral, lines AB and DC intersect in the point F and lines AD and BC B intersect in the point E. Show that the circumcircles of BCF and CDE intersect in a point G on the line EF. F A piece of cheese is cut in the shape of the sector of a circle of radius 6 cm. The thickness of the cheese is 7 cm. Find (a) The curved surface area of the cheese. (b) The volume of the cheese piece. 22 ( = ) 7 (iii) ABC is a triangle in which AB = AC and D is any point on BC. Prove that : AB2 – AD2 = BD. CD. C G 6 cm 60º 7 cm (ii) D B A D E Best Of Luck C E Paper - I MAHESH TUTORIALS S.S.C. Batch : SB GEOMETRY Chapter : 1, 2 , 6 Date : A.1. (i) MODEL ANSWER PAPER Solve the following : Length of side of cube (i) = Total surface area of a cube = = = = Test - III Marks : 30 Time : 1 hr. 15 min. 1 cm 6l 2 6 (l)2 6 (1) 6 cm2 The total surface area of cube is 6 cm2. (ii) ABC ~ DEF DEF ~ XYZ ABC ~ XYZ A = X But, m A = 70º [Given] [c.a.c.t.] [Given] m X = 70º m (arc AC) = m (arc ABC) = = m (arc ABC) = 200º A.2. (i) m ABC = 80º = ½ ½ Solve the following : Length of arc (l) measure of arc () l 4 4×9 2 r ½ ½ 1 m (arc AC) [By Inscribed angle theorem] 2 B 1 m (arc AC) 2 160º O C 360º – m (arc AC) A 360 – 160 (iii) 1 = 4 cm = 40º = × 2r 360 40 = ×2××r 360 ½ = r = 18 cm. ½ Paper - I ... 2 ... Area of the sector l ×r 2 4 × 18 = 2 = 36cm2 ½ = ½ Radius of the circle is 18 cm and Area of the sector is 36cm2. (ii) (iii) A.3. (i) In ABC, seg AQ is the median 1 BQ = QC = × BC 2 1 BQ = QC = × 10 2 BQ = QC = 5 units ......(i) AB2 + AC2 = 2AQ2 + 2BQ2 122 = 2AQ2 + 2 (5)2 122 = 2AQ2 + 2 (25) 122 = 2AQ2 + 50 2AQ2 = 122 – 50 2AQ2 = 72 AQ2 = 36 AQ = 6 units Curved surface area of a cone its radius (r) Curved surface area of a cone 1640 1640 40 l Now, r 2 + h2 402 + h2 h2 h2 h2 h Height of a cone is 9 cm. A [Given] [Given] B Q C [By Appollonius theorem] [From (i) and given] ½ ½ ½ [Taking square roots] = = = = 1640cm2 40 cm rl × 40 × l = l = = = = = = = 41 cm l2 412 412 – 402 1681 – 1600 81 9 cm [Taking square roots] ½ ½ ½ ½ ½ Solve the following : Curved surface area of a hemisphere = 905 1 cm2 7 Curved surface area of a hemisphere = 2r 2 1 22 905 = 2× × r2 7 7 ½ ½ Paper - I ... 3 ... 6336 7 6336 7 7 2 22 r2 r = 2× 22 × r2 7 ½ = r2 = 144 = 12 cm [Taking square roots] 2 3 Volume of a hemisphere = r 3 2 22 = × × 12 × 12 × 12 3 7 25344 = 7 = 3620.57 cm3 Volume of a hemisphere is 3620.57 cm3. ½ ½ ½ (ii) D A O Sol. For the smaller circle Line BE is a tangent to the circle at E and E C line CD is a secant intersecting the circle at points C and D. B BE2 = BC × BD ......(i) [Tangent secant property] In OEB, m OEB = 90º ......(ii) [Radius is perpendicular to tangent] OB2 = OE2 + BE2 [By Pythagoras theorem] 5 2 = 32 + BE2 [Given] 2 25 = 9 + BE 25 – 9 = BE2 BE2 = 16 BE = 4 units .....(iii) [Taking square roots] For the larger circle, seg OE chord AB [From (ii)] AB = 2 × BE [Perpendicular from the centre of the circle to the chord bisects the chord] AB = 2 × 4 AB = 8 units (4)2 = BC × 5 [From (i) and (iii)] 16 = BC × 5 16 BC = 5 BC = 3.2 units ½ ½ ½ ½ ½ ½ Paper - I ... 4 ... (iii) M A.4. (i) In LMN, m LMN = 90º seg MR hypotenuse LN MR2 = LR × RN .....(i) In LKN, m LKN = 90º seg KR hypotenuse LN KR2 = LR × RN .....(ii) MR2 = KR2 MR = KR R is the midpoint of seg MK L [Given] [Given] K [By property of geometric mean] [Given] [Given] [By property of geometric mean] [From (i) and (ii)] [Taking square roots] 1 A B 1 1 Solve the following : N R D C Construction : Draw seg CG. Proof : Let the circumcircle of BCF and F E G CDE intersect at points C and G. BCGF is cyclic. [By definition] m ABC = m CGF .....(i) [Exterior angle of a cyclic quadrilateral is equal to its interior opposite angle] DCGE is cyclic [By definition] m ADC = m CGE ......(ii) [Exterior angle of a cyclic quadrilateral is equal to its interior opposite angle] Adding (i) and (ii), m ABC+ m ADC = m CGF + m CGE .......(iii) ABCD is cyclic m ABC + m ADC = 180º ....(iv) [Opposite angle of a cyclic quadrilateral are supplementary] m CGF + m CGE = 180º [From (iii) and (iv)] Also, CGF and CGE are adjacent angle CGF and CGE form a linear pair [Converse of linear pair axiom] ray GF and ray GE form opposite rays Points F, G, E are collinear. G lies on line EF The circumcircle of BCF and CDE intersect in a point on line EF. ½ ½ ½ ½ ½ ½ ½ ½ Paper - I ... 5 ... (ii) 7 cm 6 cm 60º For a sector, Measure of arc () = 60º Radius (r) = 6 cm (a) Curved surface area of the cheese = Length of arc × height 2r h = 360 60 22 2 67 = 360 7 = 44 cm2 ½ ½ ½ The curved surface area of the cheese is 44 cm2. ½ (b) Volume of the cheese piece ½ = A (sector) × height r 2 h = 360 60 22 667 = 360 7 = 132 cm3 ½ ½ The volume of the cheese piece 132 cm3. ½ A (iii) In AEB, B D E m AEB = 90º [Given] 2 2 2 AB = AE + BE ......(i) [By Pythagoras theorem] In AED, [Given] m AED = 90º AD2 = AE2 + DE2 .....(ii) [By Pythagoras theorem] Subtracting equation (ii) from (i), AB2 – AD2 = AE2 + BE2 – (AE2 + DE2) AB2 – AD2 = AE2 + BE2 – AE2 – DE2 AB2 – AD2 = BE2 – DE2 AB2 – AD2 = (BE + DE) (BE – DE) AB2 – AD2 = (BE + DE) × BD .......(iii) [ B - D - E] C ½ ½ ½ ½ Paper - I ... 6 ... In AEB and AEC, m AEB = m AEC = 90º hypotenuse AB hypotenuse AC seg AE seg AE AEB AEC seg BE seg CE .....(iv) 2 2 AB – AD = (CE + DE) × BD AB2 – AD2 = CD × BD [Given] [Given] [Common side] [By hypotenuse side theorem] [c.s.c.t.] [From (iii) and (iv)] [ D - E - C] 1 ½ ½ Paper - II S.S.C. MAHESH TUTORIALS Batch : SB Date : Q.1. Test - III Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. Solve the following : 3 (i) The dimensions of a cuboid are 5 cm, 4 cm and 3 cm. Find its volume. (ii) A (ΔDEF) If DEF ~ MNK, DE = 5, MN = 6, find the value of A (ΔMNK) . (iii) Q.2. Line AB is a tangent and line BCD is a secant. If AB = 6 units, BC = 4 units, A find BD. B Solve the following : D C 6 (i) The dimensions of a cuboid in cm are 16 × 14 × 20. Find its total surface area. (ii) Find the perimeter of an isosceles right triangle with each of its congruent sides is 7 cm. (iii) Find the length of the arc of a circle with radius 0.7 m and area of the sector is 0.49 m2. Q.3. (i) (ii) Solve the following : 9 22 The surface area of a sphere is 616cm2. What is its volume ? = 7 In the adjoining figure, in the isosceles triangle PQR, the vertical P = 50º. The circle passing through Q and R cuts PQ . in S and PR in T. ST is joined. Find PST. Q P 50º S T R Paper - II ... 2 ... (iii) Q.4. (i) (ii) Prove that three times the square of any side of an equilateral triangle is equal to four times the square of an altitude. Solve the following : 12 Let the circles with centre P and Q touch each other at point A. Let the extended chord AB intersect E the circle with centre P at point E and the chord BC touches the circle with centre P at the point D.Then prove that ray AD is an angle bisector of the CAE. P D M Q C In the adjoining figure, m POQ = 30º and radius OP = 12 cm. Find the following (Given = 3.14) O (a) Area of sector O-PRQ M (b) Area of OPQ 12 cm 30º (c) Area of segment PRQ Q P (iii) B A • R 45º In the adjoining figure, if LK = 6 3 find MK, ML, KN, MN and the perimeter of MNKL. M 30º L 6 3 Best Of Luck K N Paper - II MAHESH TUTORIALS S.S.C. Batch : SB Date : A.1. (i) GEOMETRY Chapter : 1, 2, 6 MODEL ANSWER PAPER Solve the following : Length of a cuboid (l) Its breadth (b) Its height (h) Volume of a cuboid = = = = = = Test - III Marks : 30 Time : 1 hr. 15 min. 5 cm 4 cm 3 cm l×b×h 5×4×3 60 cm3 ½ Volume of cuboid is 60 cm3. (ii) DEF ~ MNK A (DEF) DE2 A (MNK) = MN2 A (DEF) 52 A (MNK) = 2 6 A (DEF) 25 A (MNK) = 36 (iii) ½ [Given] ½ [Area of similar triangles] [Given] ½ Line BCD is a secant intersecting the circle at points C and D and line BA is a tangent at A A AB2 = BC × BD 62 = 4 × BD 36 = 4 × BD 36 C B BD = 4 ½ D BD = 9 units A.2. (i) Solve the following : Length of a cuboid (l) its breadth (b) its height (h) Total surface area of a cuboid ½ = = = = = 16 cm 14 cm 20 cm 2 (lb + bh + lh) 2 (16 × 14 + 14 × 20 + 16 × 20) ½ ½ Paper - II ... 2 ... = 2 (224 + 280 + 320) = 2 × 824 = 1648 cm2 ½ Total surface area of a cuboid is 1648 cm2. ½ (ii) Given : In ABC, A m ABC = 90º AB = BC = 7 cm To find : Perimeter of ABC 7 cm Sol. In ABC, m ABC = 90º [Given] B 2 2 2 AC = AB + BC [By Pythagoras theorem] AC2 = (7)2 + (7)2 AC2 = 49 + 49 AC2 = 98 AC = 49 2 [Taking square roots] AC = 7 2 cm Perimeter of ABC Perimeter of ABC (iii) = = = AB + BC + AC 7 7 7 2 14 7 2 = 7 2 2 cm Radius of a circle = 0.7 cm Area of the sector = 0.49 m2 r Area of the sector = ×l 2 0.7 0.49 = ×l 2 49 7 = ×l 100 20 49 20 = l 100 7 l = 1.4 The length of the arc is 1.4 m. A.3. (i) Solve the following : Surface area of sphere = 616 cm2 Surface area of a sphere = 4r 2 22 616 = 4 × × r2 7 616 7 = r2 4 22 7 cm C ½ ½ ½ ½ ½ ½ ½ ½ ½ ½ Paper - II ... 3 ... r2 r = 49 = 7 cm [Taking square roots] 4 3 Volume of a sphere = r 3 4 22 777 = 3 7 4312 = 3 = 1437.33 cm3 The volume is 1437.33 cm3. (ii) ½ ½ ½ ½ P 50º S In PQR Q R [Given] seg PQ seg PR PQR PRQ ......(i) [Isosceles triangle theorem] m PQR + m PRQ + m QPR = 180º [Sum of the measures of angles of a triangle is 180º] m PRQ + m PRQ + 50 = 180º [From (i) and Given] 2m PRQ = 180º – 50º 2m PRQ = 130º m PRQ = 65º ......(ii) SQRT is cyclic PST TRQ [An exterior angle of cyclic quadrilateral is congruent to the angle opposite to adjacent interior angle] PST PRQ [P - T - R] PST = 65º (iii) T ½ ½ ½ ½ [From (ii)] To prove : 3AB2 = 4AD2 Proof : ABC is an equilateral triangle [Given] In ADB, [Given] m ADB = 90º [Angle of an m ABD = 60º equilateral triangle] m BAD = 30º [Remaining angle] B ½ ½ A ½ D C 1 Paper - II ... 4 ... ADB is a 30º - 60º - 90º triangle By 30º - 60º - 90º triangle theorem, AD = 3 AB 2 ½ [Side opposite to 60º] ½ [Squaring both sides] ½ 2AD = 3 AB 4AD = 3AB2 3AB2 = 4AD2 2 A.4. (i) Solve the following : E In MAD, MA = MD P B A D M Q C ½ [The lengths of two tangent segments from an external point to a circle are equal] [Isosceles triangle theorem] ½ m MAD = m MDA Let, m MAD = m MDA = xº ........(i) CAM ABC [Angles in alternate segments] Let, m CAM = m ABC = yº ........(ii) m CAD = m CAM + m MAD [Angles Addition property] m CAD = (x + y)º ......(iii) [From (i) and (ii)] DAE is an exterior angle of ADB m DAE = m ADB + mABD [Remote Interior angles theorem] m DAE = m ADM + m ABC [D - M - C - B] mDAE = (x + y)º ......(iv) [From (i) and (ii)] m CAD = mDAE [From (iii) and (iv)] ray AD is an angle bisector of CAE. ½ ½ ½ ½ ½ ½ (ii) Radius of the circle (r)= 12 cm O Measure of arc () = 30º M 12 cm 30º × r2 Area of sector O - PRQ = Q 360 • 30 R P = × 3.14 × 12 × 12 360 = 37.68 cm2 ½ ½ Paper - II ... 5 ... In OMP, m OMP = 90º [Given] m POM = 30º [Given and O - M - Q] m OPM = 60º [Remaining angle] OMP is 30º - 60º - 90º triangle By 30º - 60º - 90º triangle theorem 1 OP PM = 2 1 = × 12 2 PM = 6 cm. OP = OQ = 12 cm [Radii of same circle] 1 Area of OPQ = × base × height 2 1 × OQ × PM = 2 1 = × 12 × 6 2 = 36 cm2 Area of segment PRQ = Area of sector O-PRQ – Area of OPQ = 37.68 – 36 = 1.68 cm2 1 ½ ½ ½ ½ (a) Area of sector O-PRQ is 37.68 cm (b) Area of OPQ is 36 cm2 (c) Area of segment PRQ is 1.68 cm2 2 (iii) In MLK, [Given] m MLK = 90º [Given] m MKL = 30º M m LMK = 60º [Remaining angle] MLK is a 30º - 60º - 90º triangle. L By 30º - 60º - 90º triangle theorem, LK = 6 3 = MK MK 45º ½ 30º 6 3 3 MK 2 [Side opposite to 60º] 3 × MK 2 [Given] 6 3 2 3 = 12 units N K ½ = ......(i) ½ Paper - II ... 6 ... 1 × MK [Side opposite to 30º] 2 1 ML = × 12 2 ML = 6 units ......(ii) In MKN, m MKN = 90º [Given] m MNK = 45º [Given] m NMK = 45º [Remaining angle] MKN is a 45º - 45º - 90º triangle By 45º - 45º - 90º triangle theorem, 1 MK = KN = × MN ......(iii) 2 1 MK = × MN [From (iii)] 2 1 12 = × MN 2 ML = MN = 12 2 units .....(iv) KN = 12 units ......(v) [From (i) and (iii)] Perimeter of MNKL = MN + KN + KL +ML = 12 2 12 6 3 6 [From (ii), (iv) and (v) and given] = 18 12 2 6 3 Perimeter of MNKL = 6 32 2 3 units ½ ½ ½ 1 Paper - III S.S.C. MAHESH TUTORIALS Batch : SB Date : Q.1. Test - III Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. Solve the following : 3 (i) The radius of the base of a cone is 7 cm and its height is 24 cm. What is its slant height ? (ii) Determine whether 9, 40, 41 are the sides of a right angled triangle. (iii) Radius of the circle is 4 cm. What is the length of a chord of the circle ? Q.2. Solve the following : 6 (i) An arc of a circle having measure 36 has length 176 m. Find the circumference of the circle. (ii) A ladder 10 m long reaches a window 8 m above the ground. Find the distance of the foot of the ladder from the base of the wall. (iii) The perimeter of one face of a cube is 24 cm. Find (a) the total area of the 6 faces (b) the volume of the cube. Q.3. Solve the following : 9 (i) Two arcs of the same circle have their lengths in the ratio 4:5. Find the ratio of the areas of the corresponding sectors. (ii) Two circles intersect each other in points X and Y. Secants through X and Y intersect one of the circles in A and D and the other in B and C respectively. A and B are on opposite sides of line DC. Show that line AD is parallel to line BC. (iii) In the adjoining figure, PQR = 90º. T is the mid point of the side QR. Prove that PR2 = 4PT2 – 3PQ2. P Q T R Paper - III ... 2 ... Q.4. (i) Solve the following : 12 Let M be a point of contact of two internally touching circles. Let line AMB be their common tangent. The chord CD of the bigger C circle touches the smaller circle at point N and chord CM and chord DM of bigger circle intersect smaller circle at the points P and R respectively. Prove that CMN DMN. N P A R B M 10 cm 10 cm 10 cm (ii) D 60 cm A toy is a combination of a cylinder, hemisphere and a cone, each with radius 10cm. Height of the conical part is 10 cm and total height is 60cm. Find the total surface area of the toy. ( = 3.14, 2 = 1.41) (iii) In the adjoining figure, PQRV is a trapezium in which seg PQ || seg VR. SR = 4 and PQ = 6. Find VR. V Best Of Luck P 60º T 6 Q 45º S 4 R Paper - III S.S.C. Batch : SB Date : A.1. (i) MAHESH TUTORIALS Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. MODEL ANSWER PAPER Solve the following : Radius of base of cone (r) Its height (h) l2 l2 l2 l2 l = = = = = = = 7 cm 24 cm r 2 + h2 72 + 242 49 + 576 625 25 Test - III [Taking square roots] Slant height of cone is 25 cm. (ii) (iii) (41)2 = 1681 ......(i) (9)2 + (40)2 = 81 + 1600 = 1681 ......(ii) (41)2 = (9)2 + (40)2 [From (i) and (ii)] The given sides form a right angled triangle. [By Converse of Pythagoras theorem] 1 Radius of the circle is 4 cm Diameter of the circle = 4 × 2 = 8 cm Diameter is the biggest chord of the circle The length of the chord of the circle is 8 cm or less than 8 cm. A.2. (i) 1 Solve the following : Length of arc (l) measure of arc () l 176 176 176 × 10 2r = 176 m = 36º = × 2r 360 36 = × 2r 360 1 = × 2r 10 = 2r = 1760 1 ½ ½ ½ Paper - III ... 2 ... But, circumference = 2r Circumference of the circle is 1760 m. (ii) In the adjoining figure, A seg AB represents the wall seg AC represents the ladder seg BC represents the distance of the foot of the ladder from the base of the wall AC = 10 m B AB = 8 m In ABC, m ABC = 90º [Given] AC2 = AB2 + BC2 [By Pythagoras theorem] (10)2 = (8)2 + BC2 100 = 64 + BC2 BC2 = 100 – 64 BC2 = 36 [Taking square roots] BC = 6m ½ ½ C The distance of the foot of the ladder from the base of the wall is 6 m. (iii) Perimeter of one face of a cube= 24 cm Perimeter of one face of a cube= 4l 4l = 24 24 l = 4 l = 6 cm Total surface area of a cube = 6l 2 = 6 (6)2 = 6×6×6 = 216 cm2 Volume of the cube = l 3 = 63 = 216 cm3 ½ ½ ½ ½ ½ ½ ½ Total area of the 6 faces is 216 cm2 and volume of the cube is 216 cm3. A.3. (i) Solve the following : Ratio of lengths of two arcs is 4 : 5. Let the common multiple be ‘x’ Lengths of two arcs are (4x) units and (5x) units respectively Let the lengths of two arcs be ‘l1’, and ‘l2’ and Areas of their corresponding sectors be A1 and A2. l1 = (4x) units l2 = (5x) units ½ ½ Paper - III ... 3 ... Both Arcs are of the same circle. Their radii are equal Now, r = × l1 .......(i) A1 2 r A2 = × l2 ......(ii) 2 Dividing (i) and (ii) we get, A1 l1 = A2 l2 A1 4x A = 5x 2 A1 : A2 = 4 : 5 ½ ½ ½ Ratio of the areas of sectors is 4 : 5. ½ A (ii) X ADYX is cyclic XYC DAX Y D ......(i) But, XYC XBC .....(ii) DAX XBC DAB ABC line AD || line BC C B [By definition] [The exterior angle of a cyclic quadrilateral is equal to its interior opposite angle] [Angles inscribed in the same arc] [From (i) and (ii)] [A - X - B] [By Alternate angles test] ½ 1 ½ 1 P (iii) In PQR, seg PT is the median PQ2 + PR2 In PQT, m PQT PT 2 QT2 Q [Given] T R = 2PT2 + 2QT2 ......(i) [By Appollonius theorem] 1 = 90º = PQ2 + QT2 = PT2 – PQ2 1 [Given] [By Pythagoras theorem] .....(ii) Paper - III ... 4 ... PQ2 + PR2 PQ2 + PR2 PR2 PR2 A.4. (i) = = = = 2PT2 + 2 (PT2 – PQ2) 2PT2 + 2PT2 – 2PQ2 4PT2 – 2PQ2 – PQ2 4PT2 – 3PQ2 [From (i) and (ii)] ½ Solve the following : N C P D R Construction : Draw seg NR. M A B Proof :CMA CDM [Angles in alternate segments] Let, m CMA = mCDM = xº ........(i) NMA NRM [Angles in alternate segments] Let, mNMA NRM = yº .......(ii) m NMC = m NMA – m CMA [Angle Addition property] m NMC = (y – x)º ......(iii) [From (i) and (ii)] NMR DNR .......(iv) [Angles in alternate segment] NRM is an exterior angle of NDR m NRM = m NDR + mDNR [Remote interior angles] m NRM = CDM + m DNR [ C - N - D and D - R - M] y = x + mDNR [From (i) and (ii)] m DNR = (y – x)º ......(v) m NMR = (y – x)º [From (iv) and (v)] m NMD = (y – x)º ......(vi) [D - R - M] CMN DMN [From (iii) and (vi)] ½ ½ ½ ½ ½ ½ ½ ½ 10 cm 10 cm 10 cm (ii) ½ 60 cm A toy is a combination of cylinder, hemisphere and cone, each with radius 10 cm r = 10 cm Height of the conical part (h) = 10 cm Height of the hemispherical part = its radius = 10cm Total height of the toy = 60cm Height of the cylindrical part (h1)= 60 – 10 – 10 = 60 – 20 = 40 cm ½ ½ Paper - III ... 5 ... l2 l2 l2 l2 = = = = l = l = 10 2 cm Slant height of the conical part (l) = = Total surface area of the toy = = = = = = = ½ r 2 + h2 102 + 102 100 + 100 200 200 [Taking square roots] = 10 2 ½ 10 × 1.41 14.1 cm Curved surface area of the conical ½ part + Curved surface area of the cylindrical part + Curved surface area of the hemispherical part rl + 2rh1 + 2r2 ½ r (l + 2h1 + 2r) 3.14 × 10 (14.1 + 2 × 40 + 2 × 10) 31.4 (14.1 + 80 + 20) 31.4 × 114.1 3582.74 cm2 Total surface area of the toy is 3582.74 cm2. P (iii) 60º V ½ T ½ 6 Q 45º S 4 R In QSR, m QSR = 90º [Given] m SQR = 45º [Given] m QRS = 45º [Remaining angle] QSR is a 45º - 45º - 90º triangle. QS = SR [Congruent sides of 45º - 45º - 90º triangle] But, SR = 4 units ......(i) [Given] QS = 4 units .....(ii) In PQTS, seg PQ || seg TS [Given and V - T - S - R] [Given] m T = m S = 90º PQTS is a rectangle PQ = TS = 6 units .....(iii) [Opposite sides of a rectangle QS = PT = 4 units .....(iv) and from (ii) and given] ½ ½ ½ ... 6 ... In PTV, m PTV = 90º [Given] m VPT = 60º [Given] m PVT = 30º [Remaining angle] PTV is a 30º - 60º - 90º triangle. By 30º - 60º - 90º triangle theorem, 1 × PV [Side opposite to 30º] PT = 2 1 4 = × PV [From (iv)] 2 PV = 8 units ......(v) VT = 3 PV 2 [Side opposite to 60º] VT = 3 ×8 2 [From (v)] VT VR = 4 3 units .....(vi) = VT + TS + SR [V - T - S - R] VR = 4 3 64 VR = 4 3 10 VR = 2 2 3 5 units Paper - III ½ ½ ½ [From (i), (iii) and (vi)] 1 Paper - IV S.S.C. MAHESH TUTORIALS Batch : SB Date : Q.1. Test - III Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. Solve the following : 3 (i) The radius of the base of a cone is 7 cm and its height is 24 cm. What is its slant height ? (ii) In PQR, m Q = 90º, m P = 30º, m R = 60º. If PR = 8 cm, find QR. (iii) In the adjoining figure, if m APB = 30º, then m AOB ? P O B A Q.2. (i) Solve the following : 6 Find the measure of the central angle subtended by an arc of length 6.05 m and radius 5.5 m. ( = (ii) In ABC, AP is a median. If AP = 7, AB2 + AC2 = 260 then find BC. B (iii) Q.3. 22 ) 7 A P C The volume of a cube is 1000 cm3. Find its total surface area. Solve the following : (i) The curved surface area of the frustum of a cone is 180 sq. cm and the perimeters of its circular bases are 18 cm and 6 cm respectively. Find the slant height of the frustum of a cone. (ii) ABCD is a rectangle. Taking AD as a diameter, a semicircle AXD is drawn which intersects the diagonal BD at X. If AB = 12 cm, AD = 9 cm then find the values of BD and BX. 9 Paper - IV ... 2 ... (iii) Determine the values of x, y and z with P the help of information given in the adjoing figure. 4 S 6 X y Q Q.4. z Solve the following : R 12 (i) Suppose AB and AC are equal chords of a circle and a line parallel to the tangent at A intersects the chords at D and E. Prove that AD = AE. (ii) A test tube has diameter 20 mm and height is 15 cm. The lower portion is a hemisphere in the adjoining figure. Find the capacity of the test tube. ( = 3.14) (iii) In the adjoining figure, PQR = 60º and ray QT bisects PQR. seg BA ray QP and seg BC ray QR. If BC = 8 find the perimeter of ABCQ. Q 15 cm P A Best Of Luck T B C R Paper - IV MAHESH TUTORIALS S.S.C. Batch : SB A.1. (i) Marks : 30 GEOMETRY Chapter : 1, 2, 6 Date : MODEL ANSWER PAPER Solve the following : Radius of base of cone (r) its height (h) l2 l2 l2 l2 l = = = = = = = 7 cm 24 cm r 2 + h2 72 + 212 49 + 576 625 25 Test - III Time : 1 hr. 15 min. [Taking square roots] Slant height of cone is 25 cm (ii) 1 In PQR, m P = 30º m R = 60º [Given] m Q = 90º PQR is a 30º - 60º - 90º triangle By 30º - 60º - 90º triangle theorem, 1 PR [Side opposite to 30º] QR = 2 ½ ½ P (iii) 1 m (arc AB) [Inscribed angle theorem] 2 O 1 30º = m (arc AB) 2 A m (arc AB) = 60º m AOB = m (arc AB) [Definition of measure of minor arc] m APB = m AOB = 60º A.2. B ½ ½ Solve the following : (i) l 6.05 605 100 × 2r 360 22 = ×2× × 5.5 7 360 22 = × × 11 7 360 = ½ ½ Paper - IV ... 2 ... 605 × 360 × 7 100 × 22 × 11 = = 63º Measure of the arc is 63º. (ii) (iii) 1 In ABC, seg AP is the median AB2 + AC2 = 2AP2 + 2BP2 260 = 2 (7)2 + 2BP2 260 = 2 (49) + 2BP2 260 = 98 + 2BP2 260 – 98 = 2BP2 2BP2 = 162 162 BP2 = 2 BP2 = 81 BP = 9 units 1 BP = BC 2 1 9 = BC 2 BC [Given] [By Appollonius theorem] [Given] A B P ½ [ P is the midpoint of seg BC] ½ ½ = = = = = = = = 1000 cm3 l3 1000 10 cm [Taking cube roots] 6l 2 6 × 102 6 × 10 × 10 600 cm2 Total surface area of a cube is 600 cm2. A.3. (i) C [Taking square roots] = 18 units Volume of a cube Volume of a cube l3 l Total surface area of a cube ½ Solve the following : Curved surface area of the frustum of a cone = 180 cm2 Perimeters of circular bases are 18 cm and 6 cm 2r1 = 18 ........(i) 2r2 = 6 ........(ii) Adding (i) and (ii), we get 2r1 + 2r2 = 18 + 6 2 (r1 + r2) = 24 24 (r1 + r2) = 2 (r1 + r2) = 12 .......(iii) 1 1 ½ ½ ½ ½ Paper - IV ... 3 ... Curved surface area of the frustum of a cone 180 180 l = = = = (r1 + r2) l (r1 + r2) l 12 × l [From (iii)] 15 cm ½ 9 ½ ½ Slant height of the frustum of a cone is 15 cm. (ii) In ABD m BAD BD2 BD2 BD2 BD2 BD m BAD line BA is A = 90º [Angle of a rectangle] 2 2 = AB + AD [By pythagoras theorem] = 122 + 92 [Given] = 144 + 81 12 X = 225 = 15 cm [Taking square roots] B = 90º [Angle of a rectangle] a tangent to the circle at point A [A line perpendicular to the radius at its outer end is a tangent to the circle] Line AB is a tangent and line BXD is a secant intersecting at points X and D AB2 = BX . BD [Tangent secant property] 122 = BX . 15 144 = BX . 15 BX = BX = 9.6 cm In PSQ, m PSQ = 90º PQ2 = PS2 + QS2 2 6 = 42 + y 2 36 = 16 + y2 2 y = 36 – 16 y2 = 20 y = ½ C 1 ½ 144 15 (iii) D 45 ½ P [Given] [By Pythagoras theorem] 4 S 6 Q [Taking square roots] y = 2 5 In PQR, m PQR = 90º [Given] seg QS hypotenuse PR [Given] QS2 = PS × SR [By property of geometric mean] y2 = 4×x ( 2 5 )2 = 4 × x X y z R 1 Paper - IV ... 4 ... 20 x x A.4. (i) = 4×x 20 = 4 1 = 5 In QSR, m QSR = 90º QR2 = QS2 + SR2 z2 = y 2 + x2 z2 = ( 2 5 )2 + (5)2 z2 = 20 + 25 2 z = 45 z = 9×5 z [Given] [By Pythagoras theorem] [Taking square roots] 1 = 3 5 Solve the following : Construction : Draw seg BC C Proof : Take points R and S on the tangent B at A as shown in the figure line DE || line RS [Given] On transversal AD, E D EDA DAR [Converse of • alternate angles test] A S R EDA BAR .......(i) [ B - D - A] BAR BCA .......(ii) [Angles in alternate segment] EDA BCA ......(iii) [From (i) and (ii)] Similarly, we can prove that DEA CBA ......(iv) In ABC, seg AB seg AC [Given] BCA CBA ........(v) [Isosceles triangle theorem] In DEA, EDA DEA [From (iii), (iv) and (v)] seg AD seg AE [Converse of isosceles triangle theorem] AD = AE (ii) Diameter of a test tube its radius (r) Its height (h) = 20 mm 20 = 2 = 10 mm = 1 cm = 15 cm 15 cm ½ ½ ½ ½ ½ ½ 1 ½ ½ Paper - IV ... 5 ... Height of hemispherical part (h1) = = Height of cylindrical part (h2) = = = Volume of test tube = = = = = = Volume of test tube = radius of hemisphere 1 cm h – h1 15 – 1 14 cm Volume of cylindrical part + Volume of hemispherical part 2 3 r2h2 + r 3 2 r r2 h2 + 3 2 3.14 (1) 14 + 3 44 3.14 × 3 138.16 3 46.05 cm3 ½ ½ ½ ½ ½ ½ Capacity of a test tube is 46.05 cm3 (iii) Ray QT is the angle bisector of PQR [Given] P B lies on ray QT seg BA ray QP [Given] A T seg BC ray QR B BA = BC [Angle bisector theorem] But, BC = 8 units .......(i) [Given] BA = 8 units ......(ii) Q R C m PQR = 60º [Given] 1 m PQT = m RQT = × 60º [ Ray QT bisects QR] 2 m PQT = m RQT = 30º ......(iii) In BAQ, m BAQ = 90º [Given] m AQB = 30º [From (iii), P - A - Q and Q - B - T] m ABQ = 60º [Remaining angle] BAQ is a 30º - 60º - 90º triangle By 30º - 60º - 90º triangle theorem AB = 1 BQ 2 1 BQ 2 BQ = 16 units 8 = ½ ½ 1 [Side opposite to 30º] [From (ii)] ½ Paper - IV ... 6 ... AQ = 3 × BQ 2 [Side opposite to 60º] 3 × 16 2 AQ = 8 3 units AQ = ......(iv) Similarly, QC = 8 3 cm ......(v) Perimeter of ABCQ = AB + BC + QC + AQ = 888 3 8 3 [From (i), (ii), (iv) and (v)] = 16 16 3 Perimeter of ABCQ = 16 1 3 units ½ ½ ½ Paper - V S.S.C. MAHESH TUTORIALS Batch : SB Marks : 30 GEOMETRY Chapter : 1, 2, 6 Date : Q.1. Test - III Time : 1 hr. 15 min. Solve the following : 3 (i) Using Euler’s formula, write the value of V, if E = 30 and F = 12. (ii) If PQR XYZ, (iii) In the adjoining figure, chords AB and CD intersect at E. If DE = 6, BE = 3 and CE = 4, then find AE. PR 2 = and PQ = 12, then find XY. XZ 3 A C E D Q.2. B Solve the following : 6 (i) An arc of a circle having measure 36 has length 176 m. Find the circumference of the circle. (ii) Find the side of square whose diagonal is 16 2 cm . (iii) A cone of height 24 cm has a plane base of surface area 154 cm2. Find its volume. In the adjoining figure, P is the centre of the circle with radius 18 cm. If the area of the PQR is 100 cm2 and area of the segment QXR is 13.04 cm2. Find the central angle . ( = 3.14) 9 P cm (i) Solve the following : 18 Q.3. Q R X Paper - V ... 2 ... (ii) Two circles intersect each other C in points A and B. Secants through A and B intersects circles in C, D and M, N. Prove that CM || DN. A M (iii) (i) N B P In the adjoining figure, PQR = 90º. T is the mid point of the side QR. Prove that PR2 = 4PT2 – 3PQ2. Q Q.4. D R T Solve the following : 12 Let the circles with centre P and Q touch each other at point A. Let the extended chord AB intersect E the circle with centre P at point E and the chord BC touches the circle with centre P at the point D.Then prove that ray AD is an angle bisector of the CAE. P B A D M Q C (ii) A cylinder of radius 12 cm contains water upto depth of 20 cm. A spherical iron ball is dropped into the cylinder and thus water level is raised by 6.75 cm. what is the radius of the ball ? (iii) ABC is a right angled triangle C with A = 90º. A circle is inscribed in it. The lengths of the sides containing the right angle are 6 cm and 8 cm. Find the radius of the circle. 6 cm N A Best Of Luck M O L 8 cm B Paper - V MAHESH TUTORIALS S.S.C. Batch : SB A.1. (i) Marks : 30 GEOMETRY Chapter : 1, 2, 6 Date : Time : 1 hr. 15 min. MODEL ANSWER PAPER Solve the following : F+V = E+2 12 + V = 30 + 2 12 + V = 32 V = 32 – 12 (ii) 1 V = 20 PQR ~ XYZ PQ PR = XY XZ 12 2 = XY 3 12 3 XY = 2 XY = 6 × 3 [Given] [c.s.c.t.] XY = 18 units (iii) 1 Chords AB and CD intersect each other at point E inside the circle AE × BE = CE × DE AE × 3 = 4 × 6 AE = 46 3 A D AE = 8 units A.2. (i) Test - III E B 1 Solve the following : Length of arc (l) measure of arc () = = l = 176 = C 176 m 36º × 2r 360 36 × 2r 360 ½ ½ Paper - V ... 2 ... 176 = 176 × 10 2r But, circumference = = = 1 × 2r 10 2r 1760 2r ½ Circumference of the circle is 1760 m. (ii) Given : ABCD is a square. ½ A AC = 16 2 cm To find : Side of a square x Sol. ABCD is a square [Given] Let the sides of the square be x cm In ABC, B m ABC = 90º [Angle of a square] AC2 = AB2 + BC2 [By Pythagoras theorem] 2 16 2 256 × 2 x2 x2 x = x2 + x2 = 2x2 256 2 = 2 = 256 = 16 x D ½ 16 2 cm x C x [Taking square roots] The side of a square is 16 cm. (iii) ½ Height of a cone (h) = 24 cm Surface area of base = 154 cm2 1 Volume of a cone = × Surface area of base × height 3 1 = × r2 × h 3 1 = × 154 × 24 3 = 1232 cm3 ½ ½ ½ Volume of the cone is 1232 cm3. Area of sector P-QXR P = 18 cm = 100 cm2 = 13.04 cm2 = Area of PQR + Area of segment QXR Q = 100 + 13.04 = 113.04 cm2 ½ cm Solve the following : Radius of a circle (r) Area of PQR Area of the segment QXR Area of sector P-QXR ½ 18 A.3. (i) ½ ½ R X ½ ½ Paper - V ... 3 ... Area of sector 113.04 11304 11304 × 360 314 × 18 × 18 × r2 360 = × 3.14 × 18 × 18 360 = × 314 × 18 × 18 360 ½ = ½ = = 40 Central angle is 40º. ½ A C (ii) D M Construction : Draw seg AB. ½ N B Proof : ABMC is cyclic [By definition] m MCA + m MBA = 180º ......(i) [Opposite angles of a cyclic 1 quadrilateral are supplementary] ABND is cyclic [By definition] MBA ADN .....(ii) [The exterior angle of a cyclic 1 quadrilateral is equal to its interior opposite angle] m MCA + m ADN = 180º [From (i) and (ii)] m MCD + m CDN = 180º [C - A - D] seg CM || seg DN [By Interior angles test] ½ (iii) P In PQR, seg PT is the median PQ2 + PR2 = 2PT2 + 2QT2 ......(i) In PQT, m PQT = 90º PT 2 = PQ2 + QT2 2 QT = PT2 – PQ2 .....(ii) 2 2 2 2 PQ + PR = 2PT + 2 (PT – PQ2) PQ2 + PR2 = 2PT2 + 2PT2 – 2PQ2 PR2 = 4PT2 – 2PQ2 – PQ2 2 PR = 4PT2 – 3PQ2 [Given] Q T [By Appollonius theorem] R 1 [Given] [By Pythagoras theorem] [From (i) and (ii)] 1 ½ ½ Paper - V ... 4 ... A.4. (i) Solve the following : E In MAD, MA = MD P B A D M Q C [The lengths of two tangent segments from an external point to a circle are equal] [Isosceles triangle theorem] m MAD = m MDA Let, m MAD = m MDA = xº ........(i) CAM ABC [Angles in alternate segments] Let, m CAM = m ABC = yº ........(ii) [Angles Addition property] m CAD = m CAM + m MAD m CAD = (x + y)º ......(iii) [From (i) and (ii)] DAE is an exterior angle of ADB m DAE = m ADB + mABD [Remote Interior angles theorem] m DAE = m ADM + m ABC [D - M - C - B] mDAE = (x + y)º ......(iv) [From (i) and (ii)] m CAD = mDAE [From (iii) and (iv)] ray AD is an angle bisector of CAE. ½ ½ ½ ½ ½ ½ ½ ½ (ii) 6.75 cm 20 cm Radius of the cylinder (r) = 12 cm A spherical iron ball is dropped into the cylinder and the water level rises by 6.75 cm Volume of water displaced = volume of the iron ball ½ Height of the raised water level (h) = 6.75 m Volume of water displaced = r 2h ½ = × 12 × 12 × 6.75 cm3 Volume of iron ball = × 12 × 12 × 6.75 cm3 ½ Paper - V ... 5 ... 4 3 r 3 4 × 12 × 12 × 6.75 = × × r3 3 12 × 12 × 6.75 × 3 = r3 4 r3 = 3 × 12 × 6.75 × 3 r3 = 3 × 3 × 3 × 4 × 6.75 r3 = 3 × 3 × 3 × 27 r = 3 3 × 3 × 3 × 3 × 3 × 3 [Taking cube roots] r =3×3 r =9 But, Volume of iron ball = ½ ½ ½ ½ ½ Radius of the iron ball is 9 cm. (iii) C Construction : Let the sides AB, BC and ½ AC touch the circle at points L, M and N respectively. Draw seg OA, seg OB, M seg OC, seg OL, seg OM and ON. 6 cm Sol. In ABC, N [Given] m BAC = 90º O 2 2 2 BC = AC + AB [By Pythagoras theorem] ½ A B 2 2 2 BC = 6 + 8 L 8 cm BC2 = 36 + 64 BC2 = 100 BC = 10 cm .......(i) [Taking square roots] ½ Let the radius of the circle be r ½ OL = OM = ON = r .......(ii) [Radii of the same circle] seg OL side AB seg OM side BC [Radius is perpendicular to the tangent] ½ seg ON side AC Area of a triangle = 1 × base × height 2 A (AOB) = 1 × AB × OL 2 A (AOB) = .....(iii) A (AOB) Similarly, A (BOC) A (AOC) = 5r = 3r .....(iv) .....(v) 1 ×8×r 2 = 4r [From (ii)] ½ ½ ... 6 ... Adding (iii), (iv) and (v), A (AOB) + A (BOC) + A (AOC) A (ABC) 1 × AB × AC 2 1 ×8×6 2 24 r Paper - V = 4r + 5r + 3r [From (iii), (iv) and (v)] ½ = 12r [Area addition property] = 12r = 12r = 12r =2 The radius of the circle is 2 cm. ½ Paper - VI S.S.C. MAHESH TUTORIALS Batch : SB Date : Q.1. Test - III Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. Solve the following : 3 (i) Perimeter of one face of a cube is 24 cm. Find the length of its side. (ii) In DEF, m D = 90º, m E = 45º, m F = 45º. If EF = 8 2 cm, find DE. (iii) If PB = 3, PD = 4, PA = 6, find PC. A B P D Q.2. C Solve the following : 6 (i) An arc of length 4 cm subtends an angle of measure 40º at the centre. Find the radius and the area of the sector formed by this arc. (ii) A ladder 10 m long reaches a window 8 m above the ground. Find the distance of the foot of the ladder from the base of the wall. (iii) The curved surface area of a cone is 4070 cm2 and its diameter is 70 cm. What is its slant height ? Q.3. Solve the following : 9 (i) The length, breadth and height of a cuboid are in the ratio 5:4:2. If the total surface area is 1216 cm2, find the dimensions of the solid. (ii) ABCD is a parallelogram. A circle passing through D, A, B cuts BC in P. Prove that DC = DP. D A C P B Paper - VI ... 2 ... (iii) Q.4. Adjacent sides of a parallelogram are 11 cm and 17 cm. If the length of one of its diagonals is 26 cm. Find the length of the other. Solve the following : 12 (i) Suppose AB and AC are equal chords of a circle and a line parallel to the tangent at A intersects the chords at D and E. Prove that AD = AE. (ii) Adjoining figure depicts a racing track . whose left and right ends are semicircular. The distance between two inner parallel line segments is 70 m and they are each 105 m long. If the track is 7 m wide, find the difference in the lengths of the inner edge and outer edge of the track. (iii) Seg AD is the median of ABC, and AM BC. Prove that : 70 m 70 m 105 m 7m 2 2 BC (b) AB = AD – BC × DM + 2 2 105 m A BC (a) AC = AD + BC × DM + 2 2 7m 2 B 2 Best Of Luck M D C Paper - VI MAHESH TUTORIALS S.S.C. Batch : SB Date : A.1. (i) Marks : 30 GEOMETRY Chapter : 1, 2, 6 Time : 1 hr. 15 min. MODEL ANSWER PAPER Solve the following : Perimeter of one face of a cube Perimeter of one face of a cube 24 l l Test - III = 24 cm = 4l = 4l 24 = 4 = 6 The length of the side of a cube is 6 cm. (ii) 1 In DEF, D = 90º, E = 45º, F = 45º [Given] DEF is 45º - 45º - 90º triangle 1 EF DE = 2 1 8 2 DE = 2 DE = 8 cm (iii) A.2. (i) 1 Chords AB and CD intersect each other at point P outside the circle. PA × PB = PC × PD 6 × 3 = PC × 4 P 63 PC = 4 9 PC = 2 PC = 4.5 units Solve the following : Length of arc (l) measure of arc () l = 4 cm = 40º = × 2r 360 A B D C 1 ½ ... 2 ... 4 4×9 2 r Area of the sector = Paper - VI 40 ×2××r 360 = r ½ = 18 cm l ×r = 2 4 × 18 = 2 = 36cm2 ½ Radius of the circle is 18 cm and Area of the sector is 36cm2. (ii) In the adjoining figure, A seg AB represents the wall seg AC represents the ladder seg BC represents the distance of the foot of the ladder from the base of the wall AC = 10 m B AB = 8 m In ABC, [Given] m ABC = 90º 2 2 2 AC = AB + BC [By Pythagoras theorem] (10)2 = (8)2 + BC2 100 = 64 + BC2 BC2 = 100 – 64 BC2 = 36 [Taking square roots] BC = 6m ½ ½ C The distance of the foot of the ladder from the base of the wall is 6 m. (iii) Diameter of a cone Its radius (r) Curved surface area of a cone Curved surface area of a cone 4070 4070 22 × 5 l Slant height of a cone is 37 cm. ½ ½ ½ = 70 cm. 70 = 2 = 35 cm = 4070 cm2 = rl 22 35 l = 7 ½ ½ = l ½ = 37 ½ Paper - VI ... 3 ... A.3. (i) Solve the following : Ratio of the length, breadth and height of a cuboid is 5 : 4 : 2 Let the common multiple be ‘x’ Length of a cuboid = 5x cm its breadth = 4x cm and its height = 2x cm Total surface area of a cuboid = 1216 cm2 Total surface area of a cuboid = 2 (lb + bh + lh) 1216 = 2 [(5x) (4x) + (4x) (2x) + (5x) (2x)] 1216 = 20x2 + 8x2 + 10x2 2 608 = 38x2 608 = x2 38 x 2 = 16 x =4 [Taking square roots] Length of a cuboid = 5x = 5 (4) = 20 cm its Breadth = 4x = 4 (4) = 16cm and its height = 2x = 2 (4) = 8 cm Dimensions of a cuboid are 20 cm, 16 cm and 8 cm. (ii) D ABPD is cyclic DPC DAB .....(i) C P ½ ½ ½ 1 B [By definition] A [An exterior angle of cyclic quadrilateral is congruent to the angle opposite to adjacent interior angle] ABCD is parallelogram DCB DAB .......(ii) [Opposite angles of a parallelogram are congruent] DPC DCB ......(iii) [From (i) and (ii)] In DPC, DPC DCP [From (ii) and C - P - B] seg DP seg DC [Converse of isosceles triangle theorem] DP = DC ½ 1 1 ½ ½ Paper - VI ... 4 ... ABCD is a parallelogram [Given] 1 × BD .....(i) OB = OD = 2 (iii) 1 × 26 2 OB = OD = 13 cm In ADB, seg AO is the median AB2 + AD2 = 2AO2 + 2OB2 (11)2 + (17)2 = 2AO2 + 2 (13)2 121 + 289 = 2AO2 + 2 (169) 410 = 2AO2 + 338 410 – 338 = 2AO2 72 = 2AO2 AO2 = 36 AO = 6 cm 1 AO = × AC 2 OB = OD = [ Diagonals of paralle log ram bisec t each other] ½ [Given] ½ [From (i) and by definition] [By Appollonius theorem] ½ A 11 cm B 17 cm D O [Taking square roots] C ½ [ Diagonals of paralle log ram bisec t each other] 1 × AC 2 AC = 12 cm 6 = Length of other diagonal is 12 cm. A.4. (i) ½ Solve the following : C B Construction : Draw seg BC. Proof : Take points R and S on the tangent at A as shown in the figure line DE || line RS [Given] E D On transversal AD, • EDA DAR [Converse of A S R alternate angles test] EDA BAR .......(i) [ B - D - A] BAR BCA .......(ii) [Angles in alternate segment] EDA BCA ......(iii) [From (i) and (ii)] Similarly, we can prove that DEA CBA ......(iv) In ABC, seg AB seg AC [Given] BCA CBA ........(v) [Isosceles triangle theorem] In DEA, EDA DEA [From (iii), (iv) and (v)] seg AD seg AE [Converse of isosceles triangle theorem] AD = AE ½ ½ ½ ½ ½ ½ ½ 1 Paper - VI ... 5 ... (ii) 7m 105 m 70 m 70 m 105 m 7m Diameter of inner circular edge (d1) = 70 m Width of the track = 7m Diameter of outer circular edge (d2) = 70 + 7 + 7 = 84 m The inner and outer edges of the racing tracks comprises of two semicircles and parallel segments of length 105 m each 1 1 Length of outer edge = d2 + 105 + d2 + 105 2 2 = d2 + 210 = (84 + 210) m Length of inner edge Difference in the lengths of inner and outer edge ½ ½ ½ ½ 1 1 d1 + 105 + d1 + 105 2 2 = d1 + 210 = (70 + 210) m ½ = ½ = (84 + 210) – (70 + 210) ½ = 84 + 210 – 70 – 210 = 14 22 = 14 × 7 = 44 m ½ The difference in the lengths of inner edge and outer edge of the track is 44 m. (iii) (a) In AMD, m AMD = 90º AD2 = AM2 + DM2 ......(i) In AMC, m AMC = 90º AC2 = AM2 + MC2 AC2 = AM2 + (DM + DC)2 A B M D C [By Pythagoras theorem] ½ [Given] [By Pythagoras theorem] [ M - D - C] ½ ... 6 ... Paper - VI AC2 = AM2 + DM2 + 2DM × DC + DC2 AC2 = AM2 + DM2 + 2DC × DM + DC2 BC AC = AD + BC × DM + 2 2 2 2 [ From (i) and D is the midpo int of side BC ] (b) In AMB, [Given] m AMB = 90º AB2 = AM2 + BM2 [By Pythagoras theorem] AB2 = AM2 + (BD – DM)2 AB2 = AM2 + BD2 – 2BD × DM + DM2 AB2 = AM2 + DM2 – 2BD × DM + BD2 2 [ From (i) and D is the midpo int BC AB2 = AD2 – BC × DM + of side BC ] 2 ½ ½ 1 ½ ½
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