The equations are ,
,
and
.
Find the volume of the region about the -axis.
The volume of the solid is .
Substitute ,
and
.
.
The equations are ,
,
and
.
Shell method:
\Vertical axis of revolution.
\The volume of the solid is .
The distance from the center of the rectangle to the axis of revolution is .
The height of the rectangle is .
Substitute ,
and
and
in
.
.
Solve for , when
.
Substitute and
.
or
.
Therefore , the value of .
The value of .