Prove that if u is orthogonal to v and w, then u is orthogonal to cv + dw for any scalars c and d. getting started: to prove that u is orthogonal to cv + dw, you need to show that the dot product of u and cv + dw is 0. (1) rewrite the dot product of u and cv + dw as a linear combination of (u v) and (u w) using properties 2 and 3 of theorem 5.3. (2) use the fact that u is orthogonal to v and w, and the result of part (i), to lead to the conclusion that u is orthogonal to cv + dw.