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

I have to prove that 3A=(cos(2A)-cos(4A))/(sin(4A)-sin(2A))

2. Relevant equations

All of the trig identites.

3. The attempt at a solution

Well, I know I can expand tan(3A) to sin(3A)/cos(3A). After this, I have no idea what to do. I do not know any way to simplify or expand the right side of the equation. If someone can help me out by just showing the me the first step, if possible, then I can try to solve the rest of the identity by myself.

Thanks!

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

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 identity

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