1. (a) In the given figure, O is the centre of the circle and ∠AOC = 160°. Prove that 3∠y − 2∠x = 140°   2. (b) Without using mathematical tables, find the value of x if cos x = cos 60° cos 30° + sin 60° sin 30°.   3. (c) By increasing the speed of a car by 10 km/hr, the time of journey for a distance of 72 km is reduced by 36 minutes. Find the original speed of the car.