Step 1:

The expression is .

Pythagorean identity : .

Substitute in above expression.

Step 2:

Solve for .

The general solution of , then .

Where .

Substitute in .

.

Substitute in .

.

Solution for in the interval , then .

Step 3:

Solve for .

The general solution of , then .

Where .

Substitute in .

.

Substitute in .

.

Solution for in the interval , then .

Solution :

Solution for in the interval , then .