Exterior Angle of a Triangle Worksheet
Explore and apply the Exterior Angle Theorem to solve problems involving triangles at a Grade 12 level.
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Exterior Angle of a Triangle
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Read each question carefully and solve for the unknown angles. Show all your work.
1. State the Exterior Angle Theorem in your own words.
2. In the triangle below, find the measure of the exterior angle ∠ACD.
Solution:
3. The measure of an exterior angle of a triangle is equal to the sum of the measures of its interior angles.
4. If the two remote interior angles of a triangle are 45° and 65°, then the exterior angle is .
5. In triangle XYZ, if ∠X = 60° and ∠Y = 80°, what is the measure of the exterior angle at Z?
40°
100°
140°
180°
6. An exterior angle of a triangle measures 110°. If one of the remote interior angles is 70°, find the measure of the other remote interior angle.
7. The exterior angle of a triangle is always greater than either of its remote interior angles.
True
False