In isosceles triangle ABC, where sides AB and AC are equal, the exterior angle at vertex B measures 130°. What is the measure of angle A?
Show answer & explanation
Correct answer: C
Explanation
AB = AC, Exterior angle ∠B = 130°
∠B (Interior) = 180° − 130° = 50°
In the isosceles triangle, ∠B = ∠C = 50°
∠A = 180° − (50° + 50°) = 80°