1. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Warm up 1.What is the ratio of the corresponding side lengths for two congruent triangles? 2.What is the ratio of the corresponding side lengths of the two squares? 8.3 Triangle Similarity 2 cm 6 cm

2. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Section 8-3 Triangle Similarity

3. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity Postulates AA (Angle-Angle) Similarity Postulate: If two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.

4. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity 1. Are the triangles similar? 35° 105° 35° 105°

5. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity 2. Are the right triangles similar? M J H X Z Y 35° 55°

6. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity Theorems SSS (Side-Side-Side) Similarity Theorem: If the three sides of one triangle are proportional to the three sides of another triangle, then the triangles are similar.

7. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity 3. Are the triangles similar? R S 4 Q 7 7 T V 2.4 U 4.2

8. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity Theorem SAS (Side-Angle-Side) Similarity Theorem: If two sides of one triangle are proportional to two sides of another triangle and their included angles are congruent, then the triangles are similar.

9. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 8.3 Triangle Similarity Conclusion:  1   2 by Vertical Angles Theorem. 4. Are these two triangles similar?

10. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. 5. Are the triangles similar? 11 3 7 14 10 24

11. Copyright © by Holt, Rinehart and Winston. All Rights Reserved. Assignment Page 520 # 5-16 all