How to calculate a 90 degree elbow center?

If your elbow is a short radius it is 1 times your nominal pipe diameter. If it is a long radius it is 1 1/2 times your nominal pipe diameter.show me the exact pattern of long radius.

(90/2tan*Dia*1.5*25.4) (45/2tan*Dia*1.5*25.4) u will obtain Ur answer in (mm)

For 90 degree elbow (Dia*38.1) this formula used for only 90 degree elbow. For 45 degree elbow (45/2of tan*Dia*1.5*25.4) this answer obtained in (mm).