(a) Find a scalar c so that the vector is orthogonal to the vector (b) Show that if u + v and u- v are orthogonal then ||u|| = |v||- (c) Let u, v and w be three non-zero vectors. If u v=uw, show by an example that we do not necessarily have v = w. (d) Let u, U,, u, be non-zero vectors which are mutually perpendicular, in other words u-u-0 if ij. Let c, c,, c, be numbers such that Show that all c = 0. CU ++ +GU = 0.