1. Warm UP x Given that the following two pentagons are similar, find x.8 12 x 4 14 4 5 6 7 10

2. Objective
SWBAT use the AAA, SAS and SSS similarity postulates to decide which triangles are similar and find unknowns.

3. Homework
P. 433 – 434: # 5 – 9, 12 – 19

4. Congruence vs. Similarity
The match of the century!
Who will win?

5. Congruence vs. Similarity
Congruence implies that all angles and sides are equal/identical whereas...

6. Congruence vs. Similarity
Similarity implies that only the angles are congruent and the sides are proportional

7. Congruence vs. Similarity
What can be congruent?
What can be similar?

8. Back to Triangles
Since we talked about congruent triangles so much, we should mention similar triangles.

9. Back to Triangles
How could triangles be congruent?
SSS
SAS
ASA
AAS HL

10. SSS Similarity Postulate
Two triangles are similar if all three pairs of corresponding sides are proportional.

11. SSS Similarity PostulateB 21 13 9 27 C 7 A D 39 F

12. SSS Similarity Postulate
∆ABC ~ ∆EDF

13. SAS Similarity Postulate
Two triangles are similar if two pairs of corresponding sides are proportional and the included angle is congruent

14. SAS Similarity PostulateB 12 8 C 4 A D 6 F

15. SAS Similarity Postulate
∆ABC ~ ∆FED

16. AAA Similarity Postulate
Two triangles are similar if two pairs of corresponding angles are congruent

17. AA Similarity PostulateB C A D F

18. AA Similarity Postulate
∆ABC ~ ∆FED

19. Example
∆APE ~ ∆DOG. If the perimeter of ∆APE is 12 and the perimeter of ∆DOG is 15 and OG = 6, find the PE.

20. Conclusion
Congruence vs. Similarity
AAA~
SAS~
SSS~

21. Practice 10-2 Answer Example sets 2 and 3.
Be sure to include the similarity statement.