Triangle Exterior Angles and Equations
Grade 7•45 minutes•8.G.5 Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.
Learning Objective
I can write and solve equations to find missing angle measures in triangles using the exterior angle theorem.
Practice Questions
This lesson includes 7 practice questions to reinforce learning.
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1. Explain in your own words how to find a missing angle in a triangle when you know the other two angles.
2. In triangle XYZ, ∠X = 65° and ∠Y = 45°. Draw a diagram of the triangle and calculate the measure of ∠Z. [Diagram of triangle XYZ with ∠X = 65° and ∠Y = 45°]
3. Draw an isosceles triangle where the two equal angles are each 70°. What is the measure of the third angle? [Diagram of isosceles triangle with two angles of 70°]
...and 4 more questions
Educational Video
Angles of Triangle: Sum of Interior Angles and Exterior Angle Theorem by @MathTeacherGon
MATH TEACHER GON