1. 4-1 Congruent Figures 4-2 Triangle Congruence by SSS and SAS

2. Congruent Polygons
Polygons that have congruent corresponding parts – they have matching sides and angles.
When you name congruent polygons, you must list corresponding vertices in the same order.

3. Congruent Triangles
ORDER MATTERS!!! A D B E C F
Corresponding Parts

4. Example
Write six things that are congruent if:
Answers:

5. Theorem 4-1: Third Angles Theorem

6. All we need is to show 3 pairs of Corresponding Sides are congruent in order to prove Triangle Congruence.
Let’s look at a couple of two-column proofs that utilize the SSS Postulate.

7. Example 1:Using SSS

8. Try Another Proof!

9. SAS Postulate

10. Example 2: Using SAS

11. Ex 2B: Using SAS

12. Example 3: Are the Triangles Congruent?

13. Ex 3B: Are the Triangles Congruent?

14. Apply: Are these Triangles Congruent?
If congruent say why, if not explain what else you would need to know to prove them congruent by SSS or SAS.

15. Apply: Are these Triangles Congruent?
If congruent say why, if not explain what else you would need to know to prove them congruent by SSS or SAS.

16. Practice Proofs!

17. More Proofs!