Math Help - Find the angle of the circle

1. Find the angle of the circle

Find theta to 2 decimal places give that AB divides the circle's area in the ratio 5:2
http://i371.photobucket.com/albums/o...hsquestion.jpg
I have spend many hours trying to figure this out, but I have been using the AB line segment, instead of the sector of the circle. Is this correct?
I would appreciate any help given
You are given this area $\frac{2}{7}\pi r^2$
You will end up with an equation where $r^2$ drops out and you will be left only with unknown terms for $\theta$