Step:1

The trigonometric identity is $\"\"$ .

Multiply each side by $\"\"$ .

$\"\"$

Express with $\"\"$ .

$\"\"$

Simplify the identity.

$\"\"$

Multiply each side by $\"\"$ and simlify.

$\"\"$

Fundamental identities: $\"\"$ .

$\"\"$

General solution $\"\"$ :

If $\"\"$ , then $\"\"$ , where $\"\"$ is an integer.

$\"\"$ .

Solution for the range $\"\"$ .

$\"\"$ .

Solution :

The solution is $\"\"$ .