Triangle inside of circle on graph - angle problem

The question wants me to show how ∠BOC = 2(∠BAC)

__Here is the graph __

http://i686.photobucket.com/albums/v...ied__/Math.jpg

(sorry if it isn't put together all that well, I just whipped it up using the "Graph" program and "Paint")

I'm really not sure how to go about this, and what to do to solve it.

I'm a good math student, but this just has me stuck.

This is grade 10 academic math, by the way.

The unit we are working on right now is basically the Sin Law, Cosine Law, angles, solving similar triangles, etc.

Please and thank you in advance for any help! (Hi)