# Cos2x = 2 cos x sin x

1. Sep 22, 2004

### Maria

Can someone please help me with this one?

cos2x = 2 cos x sin x

I need to find 4 angles :uhh:

2. Sep 22, 2004

### Zurtex

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

3. Sep 22, 2004

### Maria

within the range of 0, 360

4. Sep 22, 2004

### Zurtex

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

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

and:

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

5. Sep 22, 2004

### Maria

I got it right... :rofl:

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