Geometric demostration of momentum transfer during high energy collision

photos:
http://ppt.cc/meOd
https://lh5.googleusercontent.com/-KS1dDli3CKU/Ujqi2aBp7tI/AAAAAAAAA2U/rrLfVCHvP0o/s800/highcollisiongeometric.jpg

(radius of circle is light speed)

To keep conservation of total momentum, energy, and mass before and after high energy collision,
geometry of various velocities is illustrated. Direction of Vf would be direction of force(momentum transfer)