In this lesson, we will learn how to complete geometric proofs using the angle sum of a triangle and find interior and exterior angles of triangles.

Students will be able to

Q1:

In a triangle 𝑋𝑌𝑍, if 𝑋𝑌=𝑋𝑍, what type of angle is the exterior angle at vertex 𝑍?

Q2:

The figure shows the exterior angles of a given triangle. Find the sum of the exterior angles.

Q3:

What is the sum of the measures of the exterior angles of a triangle?

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