Page 109 - Math Course 3 (Book 2)

Comparing Similar Figures
Mo. 9

Lesson 9 Key Concept

Corresponding Parts of Similar Figures
KEY CONCEPTS:

1. Identify corresponding parts and find Words If two figures are similar, then
missing measures of similar figures. • the corresponding angles have the
same measure, and
2. Solve problems involving indirect • the corresponding sides are
measurement using similar triangles. proportional.
Model B Y

MO. 9 - L9a
A C X Z
Finding Measures of Similar △ABC ~ △XYZ

Figures Symbols ? A ≅ ? X, ? B ≅ ? Y, ? C ≅ ? Z and
AB BC AC
= = XZ
XY
YZ
Vocabulary A-Z
Let us learn some vocabulary

Let’s Begin
similar figures
Figures that have the same shape but not
necessarily the same size are called similar
figures. Find Measures of Similar Figures
F
B Example

A C E G
The figures are similar. Find the missing measure.
D
H

indirect measurement M N
The properties of similar triangles can be used to
find measurements that are difficult to measure 3 in
directly. This kind of measurement is called
indirect measurement.
P O
x in.

x m A B
Q V

16 m
12 in.
U
10 m
D C

S T 33 in.
20 m

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