Page 119 - Math Course 3 (Book 2)

Similarity of Polygons
Mo. 10

Lesson 2 Key Concept

Similar Polygons
KEY CONCEPTS:

1. Identify similar figures. Words Two polygons are similar if and only if
2. Solve problems involving scale factor. their corresponding angles are
congruent and the measure of their
corresponding sides are proportional.
Symbol ~ is read is similar to

MO. 10 - L2a Example
B

Identifying Similar Figures 6 cm
7 cm C

4 cm
Vocabulary A-Z

Let us learn some vocabulary A 8 cm D B’
3 cm
3.5 cm C’
similar polygons
When polygons have the same shape but may be 2 cm
different in size, they are called similar polygons.
A’ 4 cm ‘D
B E

Let’s Begin
15 18 5 6

Similar Polygons
A 9 C D 3 F

When polygons are Example
similar, we use the
following notation:

Determine whether each pair of figures is similar.
△ABC ~ △DEF Justify your answer

Refers to “similar”.
K R Q

400 500

L M P

The vertex angles are marked as 40º and 50º, so
they are not congruent.

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