2021 SJI P2 Q5

The diagram below shows a circle with centre O and radius \(r\text{ cm}\). The points B, C and D lie on the circumference of the circle. F is the point of intersection of lines BD and OC and BD is perpendicular to OC.

It is given that \(\angle FOB=1.2\) radians.

1. Find BF in terms of \(r\).[1]
2. Given that the area bounded by CF, BF and the minor arc BC is \(20\text{ cm}^2\), find the value of \(r\).[5]