1. The problem statement, all variables and given/known data Show (A x B) dot (C x D) in terms of dot products only. 2. Relevant equations A x B = ABsin(theta) A dot B = AB cos (theta) 3. The attempt at a solution Subbing both those formulas into the top I got [ABsin(AtoB) times CDsin(CtoD) ] cos(between the two resultant vectors) Yet then when I try to prove it, plugging in random numbers for the four beginning vectors, it doesn't come out right... any help?