I don't know how to start solving this problem.

I have drawn the graph but have no idea to start.

A circle C cuts the x-axis at A and B, and the y-axis at P and Q. It is given that AB = 2 and major arc PQ : minor arc PQ = 3:1. The distance from the centre G of the circle C to the line x - 2y = 0 is d = 1 / (5^(1/2)).

Find the equation of the circle C.

Can anyone give me some hints?

Thank in advance.