1. The problem statement, all variables and given/known data Find the projection, P', of the point P on the line p, the distance of P from p and the coordinates of the point R symmetric to P with respect to p, where P = [1, 2, 0], and p : X = [3, 0, 0] + t(0, 1, 0), t ∈ IR. *Sorry about all the P's, but this is how the question is written. 2. Relevant equations https://en.wikibooks.org/wiki/Linear_Algebra/Orthogonal_Projection_Onto_a_Line 3. The attempt at a solution Projection of P on to p = [P ⋅ X / X ⋅X] * X = [ [1,2,0] ⋅ [3,0,0] + t(0,1,0) / [3,0,0] + t(0,1,0) ⋅ [3,0,0] + t(0,1,0) ] * [3,0,0] + t(0,1,0) I'm a bit confused with what [3,0,0] + t(0,1,0) actually means. I've usually seen the line being equal to L = cv, where v is a vector and c is some scalar. So from this I'd assume that [3,0,0] is the vector for the line, and t(0,1,0) is the scalar.