u dot v = <1,-2> dot <-4,8> u dot v = 1*(-4) + (-2)*8 u dot v = -4 - 16 u dot v = -20 The nonzero dot product tells us that u and v are not orthogonal
u = k*v <1,-2> = k*<-4,8> <1,-2> = <-4k, 8k> 1 = -4k implies that k = -0.25 -2 = 8k implies that k = -0.25 The fact we get the same k value each time tells us the two vectors are parallel (they point in the same direction on the compass). One vector is a scaled version of the other.
