Respuesta :
this was asked already
c=pid or
c=2pir
use first one
c=3pi
3pi=c=pid
3pi=pid
divide by pi
3=d
diameter=3 units
c=pid or
c=2pir
use first one
c=3pi
3pi=c=pid
3pi=pid
divide by pi
3=d
diameter=3 units