1. Warm-Up If ∆QRS  ∆ZYX, identify all 3 pairs of congruent angles and all 3 pairs of congruent sides.

2. Geometry 7-2 Similar Polygons

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

4. Definition Two polygons are similar polygons if and only if: –Corresponding angles are congruent –Corresponding side lengths are proportional

5. Example Show that the following triangles are similar.

6. Definition A similarity ratio is the ratio of the lengths of the corresponding sides of two similar polygons. The similarity ratio of ∆ABC to ∆DEF is, or. The similarity ratio of ∆DEF to ∆ABC is, or 2.

7. Definition A similarity statement is a statement that declares two figures similar. ∆ABC ~ ∆DEF