Lesson 8-2: Similar Polygons• Similar: “Same _______ – different ______”

– Think of it is ______________________

6

8

10

15

9

12

A

B

C

X

Y

Z

Look for properties about _____________ and __________________

shape size

expansion/contraction

anglessides

Two properties:

1) Corresponding angles in similar figures are

____________

2) Corresponding sides are_____________

We can write a ___________ Statement:

Corresponding means _____________

∆ _________ ~ ∆ __________

NEW SYMBOL!!! ~ MEANS _________________

congruent

proportional

matching

Similarity

ABC XYZ

“similar to

Solution:

Solution:

a) 780; corresponding angles are congruent

b) AC; corresponds to BC – sides are proportional

Check sides are proportional:

Check corresponding angles are congruent:1st figure: 120, 60, 120, 60; 2nd: 100, 80, 100, 80

NOT SIMILAR

Solution:

_______________ Ratio: the ratio of a corresponding ________ in similar figures

Example 3 Similarity Ratio = ______ = _______

Set up a proportion:

Cross-multiply & divide:

x = 16

30

12

40

x

Similarity

sides

30

12

5

2