1. The problem statement, all variables and given/known data Ex. 2. Express each of the following by an equation: (a) Two vectors A and B are parallel. (b) Three vectors A, B and C are co-planar. 2. Relevant equations C = A + B 3. The attempt at a solution I understand (a) the answer being B = (alpha)*A because that is a scalar transformation, but for part (b) the answer in the end of the book is C = (alpha)*A + (beta)*B where (alpha) and (beta) are both scalar quantities. Wouldn't it still be correct to say that C = A + B without the scalar transformation. I just don't understand why the book chose to use this answer. Thank you for any help.