Note: cos 2x is not the same as cos x times cos x.

Also, sin 2x is not sin x cos x.

I lost my previous set of text, so I give you a quick idea.

2 sin 2x = cos 2x
2 sin 2x / cos 2x = 1

(Unlike algebraic expressions like x^2 = 2x where we cannot divide both sides by x, we can divide both sides by cos 2x here)

(This is because one solution to x^2 = 2x is x = 0, which would mean that dividing both sides by x would mean that 0 is being divided by 0)

(Whereas for sin 2x and cos 2x, there will never be any instant where sin 2x and cos 2x will be 0 at the same time, so we won’t have the indeterminate 0 divided by 0 form)

What is sin divided by cos?

2 tan 2x = 1
tan 2x = 1/2

We are solving for values of x from 0 to pi, or in other words values of 2x from 0 to 2pi.

You know how to proceed?

Yup , thank for the pointers given