1. The problem statement, all variables and given/known data Hi, I wasn't sure whether to post this here or in the engineering forums. Since it's mainly math/theory I figured here would be more appropriate. Feel free to move it if it doesn't belong here. All relevant info etc. is in the picture, thanks. 2. Relevant equations 3. The attempt at a solution Ok so my problem is, how do I move on with the proof from here? Can you take the dot product between just the vector V=<Vx, Vy, Vz> and this whole big mess?