The Exterior Angle Theorem

Grade 745 minutes

Learning Objective

I can use the exterior angle theorem to solve for missing angle measures in triangles.

Practice Questions

This lesson includes 2 practice questions to reinforce learning.

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1. In triangle PQR, the exterior angle at vertex R measures 125°. If the measure of angle P is 60°, find the measure of angle Q. Show your work.

2. An exterior angle of a triangle measures 105°. One of the non-adjacent interior angles measures 38°. Find the measure of the angle adjacent to the 105° exterior angle. Explain your reasoning.

Educational Video

Exterior Angle Theorem — Formula & Examples

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