Question 341303
The center of the circle is b units from the origin. The circle has radius a.

The circle has circumference {{{2*pi*a}}}

It travels a distance {{{2*pi*b}}} around the y-axis.

By the Second Theorem of Pappus:

the surface area is {{{(2*pi*a)(2*pi*b)=4*pi^2*a*b}}}