1. The problem statement, all variables and given/known data In a certain collision problem the kinematics are determined by the following three equations: u=u1cos(@) + SQRT(2) * u2 u1sin(@)=SQRT(2) * u2 0.5mu^2=0.5mu1^2 + 0.5(2m)u2^2 Use the first two equations to express u1 and u2 in terms of u, sin(@) and cos(@). Then substitute in the third equation and obtain solutions for sin(@). 2. Relevant equations see above 3. The attempt at a solution I have that u1=u/(sin(@)+cos(@) and u2=u/(SQRT(2)((cos(@)/sin(@))+1) and substitute those in to the third equation eliminating U and m, but having tried various methods cannot solve the trigonmetry equation. Any help would be greatly appreciated.