March 11, 2013
7.1 Ratio and Proportion
ratio: compares 2 numbers by division
a:b or a to b
or
a
b
March 11, 2013
1. Write a ratio expressing the slope of the line.
A(-1,3)
B(2,-2)
March 11, 2013
2. The ratio of the side lengths of a triangle is 4:7:5,
and its perimeter is 96cm. What is the length of the
shortest side?
March 11, 2013
3. Solve each proportion.
7
x
= 56
72
x-4
=
5
20
x-4
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4. Given that 18c = 24d, find the ratio of
d to c in simplest form.
March 11, 2013
7.2 Similar Polygons: same shape but not necessarily
the same size
Two polygons are similar iff their
-corresponding angles are congruent, and
-corresponding sides are proportional
B
ABCD ~ WXYZ
X
A
W
D
C
Z
Y
similarity ratio: the ratio of the lengths of the
corresponding sides of 2 similar polygons
March 11, 2013
1. TRAP ~ ZOID. List all corr. = angles and corr. prop.
sides.
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2. Decide whether the figs are similar.
X
6
Y
9
Q
4
6
10
S
15
Z
12
W
8
T
R
March 11, 2013
4. A photo is 4 in. wide by 6 in. long. It needs to be reduced
to fit in a frame that is 1.5 in. wide. How long will the
reduced photo be?
March 11, 2013
5. A painting is similar to a wall.
a. determine the similarity ratio of the wall to the
painting
b. Find the ratio of their perimeters
18 ft
6 ft
3 ft
9 ft
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6.
ABCD ~
GBEF. Find y.
B
E
C
12
G
15
F
y
A
24
D