# Math Help - two trig proofs

1. ## two trig proofs

Proof number one:

prove that $\displaystyle \frac{cosx-sinx}{\cos2x} = \frac{cosx+sinx}{1+\sin2x}$

Proof number two:

prove that $\displaystyle \frac{1+tanx}{1-tanx} = \frac{\cos2x}{1-sinx}$

Any help is appreciated!

2. In Q1, try replacing cos 2x with cos^2 x - sin^2 x , factorise DOTS and cancel.
Then start with RHS and replace sin 2x with 2 sinx cos x and think about what you could replace the 1 with.

In Q2,
get both sides in terms of sin x and cos x only