# Cosine Proof

1. May 19, 2008

### atwarwithmaths

Hi Guys/Girls,

I have a maths exam tomorrow and there is a chance I could be asked to prove the cosine rule or sine rule.

Well I have a simple proof of the sine rule but cannot find a simple one for the cosine. They all seem very advanced.

Would anybody have a straightforward proof for the cosine rule?

Thanks,
atwarwithmaths

2. May 19, 2008

### Diffy

3. May 19, 2008

### atwarwithmaths

Thats perfect thanks.. Stupid me, I turn to wikipedia for everything else.!