The situation: In a game of pool, the white ball of mass 0.35kg travelling at 5.0ms-1 collides with a colored ball and is deflected through an angle of 33º with a velocity of 4.3ms-1. The question is a carry on (from questions about momentum and impulse) and is: What is the direction of the force the white ball exerts on the colored ball? The answer is 87.8+33º to the original direction. I found the 87.8º but I don't understand why I have to add 33º to it. Can someone explain?