The integral is
.
Rewrite the integral as
.
Consider
.
Substitute
.

Apply derivative on each side with respect to
.
.
Substiute the corresponding values in the integral.
\


Apply double angle formula :
.

.
If
then 
.
(a) Apply integration limits.
\
.
(b)
\Apply trigonometric limits in equation
.
.
If
then
.
If
then
.


.
(a) By the integration limits :
.
(b) By the limits obtained by the trigonometric substitution:
.