1. The problem statement, all variables and given/known data Vectors A and B have equal magnitudes of 57. If the sum of A and B is the vector 16.3j , determine the angle? 3. The attempt at a solution I have already gotten the answer 2•57cosθ = 16.3 cosθ = 0.143 θ = 81.8º twice that is the angle between them, or 163.6º but at first i did 2*57sinθ=16.3 since we have the y component and as far as I know y=rsinθ why is the right answer cos?