The integral is
.
Here
,
and
.
Graph the area the function of
under given intervals.
Graph :
\Graph the function
.

The above area of the graph consists of one rectangle
and one quarter circle
.
Rewrite the integral into two parts .
\
Evaluate the first integral.
\

Evaluate the second integral.
\
.
Here
is quarter circle with radius
in the interval 

Substitute
and
in
.
.
.