There are plenty of times when we need a normal vector in game dev and graphics programming (or if we are simply just learning vector math). It is relatively simple for you to find a normal (perpendicular) vector on a 2D plane. Swap the vector components and negate one, i.e. if the vector components are (u, v) swap it (-v, u) or (v, -u). Negating the first component will make the normal vector counter clock wise to the initial vector. Negating the 2nd term will make the normal clockwise to the initial vector.