Finding Four Angles Using the Cosine Double Angle Formula

[Maria]

Can someone please help me with this one?

cos2x = 2 cos x sin x

I need to find 4 angles

 

[Zurtex]

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]

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...