(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Teacher gave this identity twice to us but the starting position slightly varies.

Prove sec(2x) - tan(2x) = (cos(x)-sin(x))/(cos(x) + sin(x))

Prove cos(2x)/(1 + sin(2x)) = tan(pi/4-x)

2. Relevant equations

pretty much all trig identities

3. The attempt at a solution

I get to (1-sin(2x))/cos(2x) = (cos(x)-sin(x))/(cos(x) + sin(x)) and then I'm stumped.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Trig Indentity Help

**Physics Forums | Science Articles, Homework Help, Discussion**