The formula for projection of a vector 'b' on line represented by vector 'a' is given as the following in Linear algebra and its applications by Gilbert Strang
But why is that after finding the scalar 'x-cap' in the derivation, it is multiplied with the vector representing the line i.e. 'a' and not the unit vector along the line i.e. 'a/||a||'?
Could anyone please explain this ?