Chapter 4: Triangle Congruence Missy McCarthy Okemos High School Math Instructor

I CAN Recite and apply the Triangle Sum Theorem. Identify the exterior angle and remote interior angles of a triangle. Know and apply the Exterior Angle Theorem. Know and apply the Third Angles Theorem. Use the corollaries to the Triangle Sum Theorem to solve problems. Write geometric proofs using the Triangle Sum Theorem, Exterior Angle Theorem, and/or Third Angles Theorem as justifications.

Angles in a triangle

Proof of Triangle Sum Theorem

Example 1

What is a corollary?

Corollaries from sum theorem

More about the

Exterior Angles Theorem Plan for a proof:

Example 2

Third Angles Theorem

Example 3