Answer: ∠AOB = 100°
Explanation:
This is found in the circle geometry. The theorem in solving this stated that the angle which an arc of a circle subtends at the centre of the circle is twice that which it subtends at any point on the remaining part of the circumference of the circle
Therefore
∠AOB = 2 x ∠ACB
= 2 x 50°
= 100°