http://img231.imageshack.us/img231/7576/capturewh.jpg

I don't have an example (if someone could provide one it would be great!) but I need to figure out how to revolve around an arbitrary line.

I was given a hint that it is rotating around the bottom line not the x-axis

and that h=rsinx and i need to look at h'

h is the line going down to the x-axis