Vector Problem plz help 1. The problem statement, all variables and given/known data To prove using the vector method for any triangle ABC the statement c=acosB+bcosA holds. 2. Relevant equations[/ A.B=abcosα 3. The attempt at a solution Frankly, I don't know how to go about it. At first it seemed easy but I just coudn't somehow use the dot product twice to get acosB and bcosA. It would be greatly appreciated if you guy gave me some ideas that would help me this proof..