$\"\"$

The integral is $\"\"$ .

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

$\"\"$ .

Apply trigonometric formula of integration: $\"\"$ .

$\"\"$

$\"\"$ . $\"\"$

Check the solution by using differentiation.

Consider $\"\"$ .

Apply derivative on each side with respect to $\"\"$ .

$\"\"$

$\"\"$ .