Relative angle between two balls with equal mass after collision

[Phunee]

I´m working on a physics hand-in and found the relative angle between the two balls after collison(where one is stationary before the collison) to be exactly 90degrees, is this random or is it always so?
It´s worth mentioning that total momentum and kinetic energy is conserved.

The hand in is attached and the problem I´m referring to is problem 3

 

[A.T.]

https://www.physicsforums.com/threads/2d-elastic-collisions-with-equal-masses.178210/

 

[Nugatory]

A.T. has provided a link to the previous discussion of this problem. We can close the thread, and if there are any more questions start a new thread in the physics homework sub forum.