# Math Help - sin(4x)/1+cos(4x)=tan(2x)

1. ## sin(4x)/1+cos(4x)=tan(2x)

I would like to do more research on this type of question. what is the topic called?

also if anyone could help me with the question please.

2. Trigonometric Identities...

3. Originally Posted by decoy808

I would like to do more research on this type of question. what is the topic called?

also if anyone could help me with the question please.
The given identity is easily proved using the double angle formula for sin and cos.

4. need help from here. trying to cancel out LHS and RHS but cannot seem to get tan(2x)

5. Originally Posted by decoy808

need help from here. trying to cancel out LHS and RHS but cannot seem to get tan(2x)
LHS = $\frac{2 \sin(2x) \cos(2x)}{1 + \cos^2(2x) - \sin^2(2x)} = ....$

6. Uhm... well, it would be easier to consider an y = 2x.
$\frac{sin\, 4x}{1+cos\, 4x}=tan\, 2x \Leftrightarrow \frac{sin\, 2y}{1+cos\, 2y}=tan\, y$