The trigonometric equation is .

Pythagorean identity : .

Subtract from each side.

.

Factorize the above equation.

Apply zero product property.

or

or .

Solve .

The general solution of is , where is an integer.

The solution is , where is an integer.

Find the solutions on the interval .

If , .

If , .

If , .

If , .

Thus, the solution is on the interval .

Solve .

The solution is , where is an integer.

Find the solutions on the interval .

If , .

If , .

If , .

If , .

Thus, the solutions are and on the interval .

Therefore, the solutions of are , , and on the interval .

Check :

The equation is .

Substitute in .

Since the above statement is true, is a solution of .

Substitute in .

Since the above statement is true, is a solution of .

Substitute in .

Since the above statement is true, is a solution of .

The solutions of are , , and on the interval .