Show that the orthogonal projection of a vector y onto a line L through the origin in R² does not depend on the choice of the nonzero u in L used in the formula for ŷ. To do this, suppose y and u are given ŷ and  has been computed by formula (2) in this section. Replace u in that formula by cu, where c is an unspecified nonzero scalar. Show that the new formula gives the same ŷ.