例2证明向量c与向量(a·Cb-(b·c)a垂直 证(a·c)b-(b·c)d =[(a·c)b:c-(b·c)l·dl =(b)·c-a·q 0 I(a·c)b-(b·cd|Le例 2 证明向量c 与向量 a c b b c a       (  ) − (  ) 垂直. 证 a c b b c a c        [(  ) − (  ) ] [(a c)b c (b c)a c]         =   −   (c b)[a c a c]       =   −  = 0 a c b b c a c        [(  ) − (  ) ]⊥