The integral is .
The indicated trignometric subustitution is .
Subustiute and
.
.
Trigonometric identity : .
Consider .
Apply derivative on each side with respect to .
.
Subustiute and
in the integral.
Sum and difference rule of integration :.
Substitute in the above integral.
.
The indicated trignometric subustitution is .
In the right triangle and
.
Find .
Therefore, substitute in equation
.
.
Associate Right Triangle :
\.