Question

In Fig. O is the centre of the circle. 

Find ∠BAC.

Answer 1

We have, 

∠AOB = 80° 

∠AOC = 110° 

∠AOB + ∠AOC + ∠BOC = 360° 

(Complete angle)

80° + 110° + ∠BOC = 360°

∠BOC = 170°

By degree measure theorem,

∠BOC = 2∠BAC

170° = 2∠BAC

∠BAC = 85°