"Grunff" wrote in message
...
Andy Hall wrote:

You're absolutely right pi x d provides the circumference.


Also provides the area for circles where d = r^2 - so your original
formula would work fine for pipes of 2cm diameter :-)


Err........... don't you mean 4cm diameter?
Thus radius = 2 and radius squared = 4 = diameter
(numerically, that is)

David