4-1 Congruent Figures 4-2 Triangle Congruence by SSS and SAS
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.
Congruent Triangles ORDER MATTERS!!! A D B E C F Corresponding Parts
Example Write six things that are congruent if: Answers:
Theorem 4-1: Third Angles Theorem
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.
Example 1:Using SSS
Try Another Proof!
SAS Postulate
Example 2: Using SAS
Ex 2B: Using SAS
Example 3: Are the Triangles Congruent?
Ex 3B: Are the Triangles Congruent?
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.
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.
Practice Proofs!
More Proofs!