How is bend length calculated when using induction pipe bending machine?

How is bend length calculated when using induction pipe bending machine?

Lf = the flat length of the metal plate.
BA = bending allowance.
BD = bend deduction.
R = internal bending radius.
K = K factor, which is t /T.
T = material thickness.
t = the distance from the inner surface to the neutral line.
A = bending angle (in degrees) (the angle at which the material is bent)