In the given figure, O is the centre of a circle and ∠AOB = 140°. Then, ∠ACB = ?
Given: ∠AOB = 140°
Here,
(Exterior ∠AOB) = 360° – (interior ∠AOB)
(Exterior ∠AOB) = 360° – 140°
(Exterior ∠AOB) = 220°
We know that,
(Exterior ∠AOB) = 2 × ∠ACB
220° = 2 × ∠ACB
∠ACB = = 110°
∴ ∠ACB = 110°