Question

Given: △ABC, m∠A=120°, AB=AC=1
Find: The radius of circumscribed circle

Answer 1

9514 1404 393

Answer:

1

Explanation:

Angle B of isosceles triangle ABC is (180° -120°)/2 = 30°, so arc AC of the circumscribed circle has a measure of 2B = 60°. A chord that subtends a 60° arc is the same length as the radius, so the radius is 1.