1. The problem statement, all variables and given/known data Scalar product of vectors AB = -6; vector product of AB = 9. Find the angle between vectors A and B. 2. Relevant equations Scalar product: cos(θ)*AB Vector product: sin(θ)*AB (sin(θ))/cos(θ) = tanθ 3. The attempt at a solution AB = -6/cos(θ) AB = 9/sin(θ) 9/sin(θ) = -6/cos(θ) 9/-6 = (sin(θ))/cos(θ) 3/-2 = tan(θ) tan^-1(3/-2) = -56° which I take to mean 56° from each other. But their answer is 124° which is -56° + 180°. How can this be when the whole time we are dealing with one angle between two vectors?