Math 9 Date: _____________________ Section 7.3 – Similar Polygons Page 1 of 2 Learning Intentions:

• I can determine if two polygons are similar.

Definitions: A Polygon is an enclosed figure with at least three sides.

When one polygon is an enlargement or a reduction of another polygon, the polygons are similar.

We use the following symbol to indicate similarity: _______

Similar polygons have the same shape, but not necessarily the same size. They must have:

• Corresponding angles being equal.

• Corresponding sides are proportional.

Here polygon ABCDE polygon FGHIJ The corresponding angles are: The corresponding sides are: Example 1: Decide if each pair of polygons is similar. Show your reasoning. (a) CDEF and RSTU are parallelograms. (b)

Math 9 Date: _____________________ Section 7.3 – Similar Polygons Page 2 of 2 If you know two polygons are similar, you can use corresponding sides and angles to determine missing measurements. Example 2: Given ABCD EFGH Find each of the following: (a) ∠E (b) ∠G if ∠C = 100 o . (c) EF (d) CD (e) The scale factor of image (f) The scale factor of image ABCD to EFGH . EFGH to ABCD . Example 3: Given ABCD EFGD with AB = 10cm, AD =6 cm, and AE = 2 cm, determine EF. Practice Questions: Page 341: 6__, 9__, 10__, 11__, 14__, 17__