In the figure, A, B, and C are three points on a circle with centre O such that ∠BOC = 30° and ∠AOB = 60°. If D is a point on the circle other than the arc ABC, find ∠ADC.

Here, ∠AOC = ∠AOB + ∠BOC ⇒ ∠AOC = 60° + 30° ⇒ ∠AOC = 90°
We know that the angle subtended by an arc at the center is double the angle subtended by it at any point on the remaining part of the circle.
⇒ ∠ADC = 1/2 ∠AOC = 1/2 × 90° = 45°