With v = (1,0) and w = (1,5), choose a number c so that w - cv is perpendicular to v. Then find the formula for c starting from any nonzero v and w.
a) c = 1 ; c = 5/2
b) c = 0 ; c = 1
c) c = 2 ; c = (1/5)
d) c = (5/2) ; c = 1