Ratios in Similar Polygons p. 244 in your book Thursday August 8th 2013 Unit 1; Module 8-1 Ratios in Similar Polygons p. 244 in your book Holt McDougal Geometry Holt Geometry

Warm Up / Prior Knowledge 1. If ∆QRS  ∆ZYX, identify the pairs of congruent angles and the pairs of congruent sides. Solve each proportion. 2. 3. Q  Z; R  Y; S  X; QR  ZY; RS  YX; QS  ZX x = 9 x = 18

Objectives Identify similar polygons. Apply properties of similar polygons to solve problems.

Vocabulary 1) congruent (review from Alg I CC) having the same size & shape, denoted by 2) similarity ratio the ratio of the lengths of the corresponding sides of 2 similar polygons 3) 3rd Angle Theorem if 2 angles of one triangle are congruent to 2 angles of another triangle, then the 3rd angles are also congruent

4) Figures that are similar (~) have the same shape but not necessarily the same size.

5) Similar polygons 2 polygons whose corresponding angles are congruent and whose corresponding side lengths are proportional

Example 1: Describing Similar Polygons Identify the pairs of congruent angles. 0.5 N  Q and P  R. By the Third Angles Theorem, M  T.

Example 1: Describing Similar Polygons Identify the pairs of corresponding sides. 0.5

TRY THIS ON YOUR OWN! Example 1 Identify the pairs of congruent angles and corresponding sides. Angles: B  G , C  H , A  J. Sides:

Tonight’s HW Assignment At home, everyone needs to log on to MY eCLASS and make sure you can get into the online textbook