[SOLVED] Identities Help? Thanks!

Ok, our teacher has been very busy lately so he hasn't been around to help us and he isn't available after/before school at the moment. So here i am XD

This one i have no clue where to begin:

Quote:

Prove that each side of the equation equals each other (or something like that, i don't have the book infront of me)

1-2cos^2(x)+cos^4(x)=sin^4(x)

*I'd assume that you have to factor the cos's but i have no clue how to do that*

I also don't know where to begin with this one..

(1-sin^2(x))(1+sin^2(x))=2cos^2(x)-cos^4(x)

*Again i'd assume u have to factor the cos's into something?*

Thanks for ANY help anyone can give!!!