Answer:

Explanation:
This is a trigonometric equation where we need to use the cosine of the double-angle formula

Replacing in the equation

We have

Rearranging

A second-degree equation in cos2x. The solutions are:

For the first solution
cos2x=1 we find two solutions (so x belongs to [0,2\pi))

Which give us

For the second solution

We find four more solutions

Which give us

All the solutions lie in the interval

Summarizing. The six solutions are
