9. Let v and w be nonzero vectors of the inner product space (V, (, )), and let e be the angle between them. Prove the following equivalence: Il v + wll = llvil + II wll if and only if 0 = 0. Your proof should be a chain of equivalences with each step justified. Hint The equality is true if and only if it is true after squaring both sides. (Why?) Use the definition lv t wll' = (vtw,v+ w) and expand the inner product