1. The problem statement, all variables and given/known data The problem is here: http://imgur.com/aKBkz" [Broken] 2. Relevant equations 3. The attempt at a solution http://imgur.com/0jyRD" [Broken] I think i solved it correctly but I wanted to make sure since I'm pretty terrible with proofs. I was wondering if you have to assign values to vector A such as <a1,a2,a3> and then cross product everything out. Would that be valid since you dont know how big the vector is going to be?