$\"\"$

The integral is $\"\"$ .

$\"\"$

The trignometric identity is $\"\"$ .

$\"\"$

Let $\"\"$ then $\"\"$ .

$\"\"$

Apply the sum and difference rule of integration : $\"\"$ .

$\"\"$

Power rule of integration : $\"\"$ .

$\"\"$

Subustiute $\"\"$ in above equation.

$\"\"$

Thus, $\"\"$ .

$\"\"$

$\"\"$ .