What is the ratio of the area of sector AOB to the area of sector COD?

Question

1/3,1/4,1/9,3/8

Answer 1

Since the area is 1/2 r^2 θ, the ratio is

1/2 r^2 m∠AOB
--------------- = (m∠AOB)/(m∠COD)
1/2 r^2 m∠COD

That is, since for a given circle, the area is directly proportional to the angle, the ratio of the areas is the same as the ratio of the angles.

I have no idea what that ratio is, but it must be one of the choices.