Objective: Short cuts for similar triangles.

Warm up

2

3a. Is this an enlargement or a reduction? Explain.

b. What scale factor do you think this is? Explain.

c. What angle is the same size as angle OBA? Explain.

Investigation: AA

1

2

3.

4

SSS: Three sets of corresponding sides are in proportion.

SAS: an angle is congruent to a corresponding angle. The lenghts of sides including these angles are in proportion.

Example 1Are the triangles similar. Justify your answer.a.

b.

c.

Similar Triangles ConjecturesAA

SSS (three sets of corresponding sides are in proportion)

SAS (two sets of corresponding sides are in proportion and the angles they include are congruent)

Assignment: worksheet # 1-15