Exploring Angles in Triangles

1. In triangle ABC, angle A = 50°, angle B = 60°. What is the measure of angle C?

• 80°

• 70°

• 90°

• 40°

2. In triangle DEF, angle F = 70°. If the exterior angle at vertex D is 110°, what is the measure of angle E?

• 40°

• 60°

• 50°

• 30°

3. Calculate the exterior angle at vertex X of triangle XYZ if angle Y = 40° and angle Z = 60°.

• 90°

• 80°

• 120°

• 100°

4. Triangle PQR has angles P = 45° and Q = 55°. What is the measure of the exterior angle at vertex R?

• 75°

• 90°

• 100°

• 120°

5. If the sum of the interior angles of triangle ABC is 180°, and angle A = 30°, what is the measure of angle B if angle C is 90°?

• 75°

• 120°

• 60°

• 45°

6. In triangle GHI, angle G = 80° and angle H = 30°. What is the measure of the angle I?

• 120°

• 100°

• 70°

• 90°

7. Calculate the exterior angle at vertex A of triangle ABC if angle B = 45° and angle C = 55°.

• 100°

• 90°

• 80°

• 120°

8. Triangle MNO has angles M = 60° and N = 70°. What is the measure of angle O?

• 50°

• 90°

• 80°

• 40°

9. In triangle STU, angle S = 40° and angle T = 100°. What is the measure of the exterior angle at vertex U?

• 160°

• 90°

• 120°

• 140°

10. Calculate the exterior angle at vertex P of triangle PQR if angle Q = 15° and angle R = 55°.

• 70°

• 90°

• 80°

• 120°