In the figure XY and X'Y' are two parallel tangents to a circle with centre O and another tangent AB with point of contact C interesting XY at A and X'Y' at B, what is the measure of ∠AOB.
This question is exactly same as Ex 10.2, 9 – Chapter 10 Class 10 – Circles
Please check https://www.teachoo.com/1835/539/Ex-10.2--9---In-fig--XY-and-X-Y--are-two-parallel-tangents/category/Ex-10.2/