Geometry
Chapter 10 Review – ANSWER KEY
1) Find the area of the following:
(a)
(b)
A = (10)(8) = 80 units2
(d)
(c)
A = (½ )(8)(8 + 15) = 92 cm2
A = (½)(24)(5) = 60 ft2
(e) Regular Pentagon:
A = ½ (24)(10) = 120 units 2
A = ½(75)(10.3) = 386.25 cm2
2) Find the area of a regular decagon with perimeter 30m
A = ½(30)(4.62) = 69.3 m2
3) Find the area of a regular pentagon with radius 2 cm.
A = ½ (5.85)(1.62) = 4.74 cm2
4) Find the (a) Circumference and the (b) Area of the circle:
C = 2π(6) = 12π units
A = π(6)2 = 36π units2
5) Consider the circle at right:
(a) Find the Arc Length of PQ
Arc Length =
(2π(2)) = 2.51 units
(b) Find the area of the sector PNQ
Area of Sector =
π(2)2 = 2.51 units-2
6) Find the area of the shaded region:
Area of Shaded Region = Area of Sector – Area of Triangle
Area of Sector =
π(7)2 = 25.656…
Area of Shaded Region = 4.3 units2
Area of Triangle = ½(7)(6.1) = 21.35
7) Find the probability of hitting the shaded region in the figure: (assume the circles are all
congruent)
Prob = (desired area)/(total area)
Total Area = (20)(2) = 400 in2
20 inches
Desired Area = 400 - 100π = 85.84
P(shaded) = (85.84)/400 = 21.5%
20 inches