[FONT=Verdana,Arial,Helvetica]piRRh/3
Basically, you multiply together [/FONT][FONT=Verdana,Arial,Helvetica]piRRh and a third of that quantity is the right answer. It doesn't matter whether you multiply by 1/3, divide by three, or multiply by .3333333333....., you are doing the same thing. Though, do one of the first two, cause on a calc it will give you the most accurate answer.