Sine Law and Cosine Law

I'm going nuts! If I can prove the Sine and Cosine Law and pass it on Monday by 1:40pm GMT+08 in my Math class, then I can gain 2 bonus points for my Math 4 periodical exam (believe me, 2 points are a luxury in my school). However, I'm having a mental block... so... ideas go boing! from my head.

Here's the Cosine Law (capitals for lengths, and lowercase for the angle):

A2 = B2 + C2 - 2BCcosa.

A-squared is equal to B-squared plus C-squared minus 2 (B) (C) cosine angle-alpha.

Thanks!

Oops... sorry. Didn't see this.

Here's the proof, if you're still curious:

http://www.cut-the-knot.org/pythagoras/cosine.shtml

Oh, thanks anyway.

The proof there is different from the one I found... hmm. It's true that there is more than one approach to every problem.

Oh yes! The higher you go in math, the more proofs there are. It's crazy, really.