2. Learning Targets
I can identify similar polygons.
I can write similarity statements.
I can find missing parts of similar figure.

3. Vocabulary
similar figures – have the same shape but not necessarily the same size
scale factor – the ratio of corresponding linear measurements of two similar figures
scale drawing – a drawing in which all lengths are proportional to corresponding actual lengths

4. Scale and Ratio Examples
Real World
Scale and Ratio Examples

7. Similar Polygons
corresponding parts
similarity statement

8. Example 1

9. Example 2 Find corresponding sides by locating congruent angles.
EA = 12 = ED = 12 = AB = 18 = DC = 18 = ED = 12 = 2
ST TU RS VU TU
YES, The polygons are similar. ABCDE ~ SRVUT, the scale factor is 2:1.

10. Example 3

11. Example 4 12 x Begin by writing a ratio involving the variable. 20 10
Choose two corresponding parts that have values (numbers).
Create a proportion and solve for the variable.
20 = 12 x
20x = 120
x = 6