hey >>> i want to Calculate this area Equation : A= pi *(D^2*d^2)*p*n*k n= 0.5 k=0.4 but the Valuable of ( D-d-p) given like this : D:d:p 4 1 4 My question is : i dont understand Valuable of ( D-d-p) is it Number or proportion ... just can any one make it clear to me Please, Please, Please,