Question

In a Δ ABC, if ∠A = 120° and AB = AC. Find ∠B and ∠C.

Answer 1

Given,

∠A = 120°

AB = AC

We have to find ∠B and ∠C:

We can observe that Δ ABC is an isosceles triangle since AB = AC

∠B = ∠C (Angle opposite to equal sides are equal) [i]

We know that,

Sum of angles in a triangle is equal to 180°

∠A + ∠B + ∠C = 180°

∠A + ∠B + ∠B = 180°

∠A + 2∠B = 180°

120° + 2∠B = 180°

2∠B = 180° – 120°

2∠B = 60°

∠B = 30°

∠B = ∠C = 30°