Method 1:

The integral is .

Let

Apply the derivative on each side with respect to .

.

Substitute and in .

.

Substitute .

.

.

Method 2:

The integral is .

Let

Apply the derivative on each side with respect to .

.

Substitute and in .

.

Substitute .

.

.

Method 3:

The integral is .

Apply the double-angle formula: .

.

Let

Apply the derivative on each side with respect to .

.

Substitute and in .

Substitute .

.

.  

or

or

.