Let ABC be a triangle such that ∠ABC = 70° and ∠ACB = 50°. Let O be the incentre of the triangle. Find ∠BOC.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 120°.
∠A = 180° - (∠ABC + ∠ACB) = 180° - (70° + 50°) = 180° - 120° = 60°
∠BOC = 90° + (∠A/2) = 90° + (60°/2) = 90° + 30° = 120°