The curve is and the interval is
.
The surface area formula, for rotation about the -axis is
.
.
Rewrite expression as .
.
Differentiate the function with respect to .
Substitute corresponding values in .
The surface area :
\
\
Consider . \ \
Change of integral limits:
\If then
.
If then
.
Substitute corresponding values in .
.
Therefore, the exact area of the surface by rotating the curve about the -axis is
.
The exact area of the surface by rotating the curve about the -axis is
.