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SchoolNova Math3
Unit 17A CW
Write down the expressions
1
Hannah had A stickers. She gave B stickers to C friends. How
many stickers does she have left?
Zack needs X cupcakes. He already has Y vanilla and X chocolate
cupcakes. How many more should he buy?
Jenny saved A dollars this week. She saved 3 times as much last
week and 4 times less the week before. How much money does she
have?
A class went on a field trip, they took X buses that fit Y students
each and Z cars that fit W students each. How many students went
on the trip?
Pavel was collecting coins. He got A from his piggy bank, and B
from his brother. He lost C and gave D to his friend. How many
coins does Pavel have?
2
More about the perimeter
Sometimes the shape is more complicated then the square, triangle or pentagon. What
we need to do in that case?
In this case you need to calculate 'missing' lengths and be particularly careful to include
all the sides.
The diagrams show the plan view of a small pool. Can we find the perimeter of the
pool?
2m
?
14 m
8m
14 m
?
8m
?
5m
5m
5m
5m
2
5
Calculate the perimeter of the square ABCD and the rectangle MKPL if you
know the length of the red side and that both shapes consist only of squares.
A
5 cm
D
6
M
B
K
8 cm
L
C
P
y
How can we write the expression for the
perimeter of that rectangle?
x
P = __________________________
7
Write the expression for the perimeter of given squares.
8 cm
P = ______________
7
x cm
P = _______________
x – 6 cm
P = ________________
Commutative Property of Addition and Multiplication
Commutative Property of Addition states that changing the order of the addends will not
affect the sum: a + b = b + a
Commutative Property of Multiplication states that changing the order of the factors will
not affect the product: a × b = b × a
Calculate the most convenient way:
90 + 60 + 30 + 40 +80 + 70 + 20 + 10 = ______
80 × 5 × 7 × 200 = _______________________
126 × 50 × 25 × 4 ×20 × = ________________
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Is there a quadrilateral that has only 3 right angles? Why not?
5
Examine the picture. What is the difference between the quadrilaterals V
and VI and the other quadrilaterals on the picture? What kind of angles do they have?
Quadrilateral
Rectangle
A four-sided polygon. The sum of the
angles of a quadrilateral is 360 degrees
A four-sided polygon having all right
angles. The sum of the angles of a
rectangle is 360 degrees.
Square
Parallelogram
A four-sided polygon having equal-length
sides meeting at right angles. The sum of
the angles of a square is 360 degrees
A four-sided polygon with two pairs of
parallel sides. The sum of the angles of a
parallelogram is 360 degrees.
Rhombus
Trapezoid
A four-sided polygon having all four sides A four-sided polygon having exactly one
of equal length. The sum of the angles of a pair of parallel sides. The two sides that are
rhombus is 360 degrees.
parallel are called the bases of the
trapezoid. The sum of the angles of a
trapezoid is 360 degrees
4 × 180º – 360º = 360º
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9
Draw a Venn diagram for:

Square, Parallelogram, Rectangle

Triangle, Parallelogram , Square, all shapes

Rectangle , Rhombus, Trapezoid, Parallelogram

Quadrilateral, Rectangle, Rhombus, Trapezoid, Parallelogram, Square

Triangle, Parallelogram , Square, Circle, all shapes
5
Measures and Fractions of Areas:
c
b
a
e
d
V
Q
P
T
S
R
W
Q = ☐b
P = 4a
a=
1
4
P
b=
V = ☐e
e=
R = ☐b
Q
b=
R
S = ☐b
T = ☐c
b=
c=
S
T
W = ☐d
V
e=
W
To find one n-th fraction of a number or any other object this object has to be divided
into n equal parts.
For example:
One of the ways to find one n-th fraction of a rectangle is to cut it into n equal strips.
1:2=
1
1
×2=
2
1:3=
1
2
1
1
×3=
3
1:5=
1
3
1
1
×5=
5
1:7=
1
5
1
1
×7=
7
1
7
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