# Cos2x = 2 cos x sin x

Maria

## Main Question or Discussion Point

cos2x = 2 cos x sin x

I need to find 4 angles :uhh:

Zurtex
Homework Helper
Within what range of x? And have you checked what I posted to this problem in the other thread?

Maria
within the range of 0, 360

Zurtex
Homework Helper
Well this is easily solvable as long as you remember these 2 identities:

$$\sin 2 \theta \equiv 2 \cos \theta \sin \theta$$

and:

$$\tan \theta \equiv \frac{\sin \theta}{\cos \theta}$$

Maria
I got it right... :rofl: