$\"\"$

The trigonometric identity is $\"\"$ .

Consider $\"\"$ . \ \

$\"\"$

Apply pythagorean identity: $\"begin$ then $\"\"$ .

Substitute $\"\"$ in the above equation.

$\"\"$ \ \

Substitute $\"begin$ in the above equation.

$\"\"$

Multiply and divided numarator and denominator by $\"\"$ .

$\"\"$

$\"\"$ .

$\"\"$

$\"\"$ .