3. (Strang 4.1.28) Explain why each of these statements is false: (a) a = [1,1,1] is perpendicular to 6 = [1, 1, −2], so the planes a³r = x + y + z = 0 and br=x+y-2z = 0 are orthogonal subspaces of R³. (b) The subspace of R5 spanned by (1, 1, 0, 0, 0) and (0, 0, 0, 1, 1) is the orthogonal com- plement of the subspace spanned by (1, -1, 0, 0, 0) and (2, -2, 3, 4, -4). (c) Two subspaces that meet only at the zero vector must be orthogonal.