Step 1 :

Find $\"\"$ .

The function $\"\"$ .

The point $\"\"$ is on the circle.

$\"\"$ .

Compare the equation with $\"\"$ .

Radius of the circle $\"\"$ .

The point $\"\"$ is on a circle of radius 1.

From the figure, angle $\"\"$ lies in third quadrant.

$\"\"$

Half-angle formula : $\"\"$

$\"\"$ .

$\"\"$ (Since $\"\"$ lies in third quadrant.)

$\"\"$

$\"\"$ .