1. 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 __________________ shapesize expansion/contraction angles sides

2. 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 ABCXYZ “similar to

3. Solution: a) 78 0 ; corresponding angles are congruent b) AC; corresponds to BC – sides are proportional Check sides are proportional: Check corresponding angles are congruent: 1 st figure: 120, 60, 120, 60; 2 nd : 100, 80, 100, 80 NOT SIMILAR

4. Solution: _______________ Ratio: the ratio of a corresponding ________ in similar figures Example 3 Similarity Ratio = ______ = _______ Set up a proportion: Cross-multiply & divide: x = 16 Similarity sides