Question

In ∆ABC, ∠A = 70° and AB = AC. Find the value of B and C.

Answer 1

When two sides AB and AC are equal, then their opposite angles ∠B and ∠C will also be equal.

∵∠A = 70°

∵ Sum of all three angles in a triangle = 180°

∠A+∠B +∠C = 180°

⇒ 70° + ∠B +∠B = 180° [∵ ∠B = ∠c]

⇒ 2∠B = 180° – 70° = 110°

∴ ∠B = 110/2 = 55° =∠C