Question

In the following figure, O is the centre of the circle. Find the values of a, b, c and d

Answer 1

∠AOB = 2∠AOB

= 2 × 50°

= 100°

(Angle at the centre is double the angle at the circumference subtended by the same chord)

Also, OA = OB

`=>` ∠OBA = ∠OAB = C

∴ `c = (180^circ - 100^circ)/2 = 40^circ`