(a1,a2,a3)×(b1,b2,b3)=(a2b3-a3b2,a3b1-a1b3,a1b2-a2b1)
因为(1,2,3)x(4,5,6)=(2*6-3*5,3*4-1*6,1*5-2*4)=(-3,6,-3)
(1,2,3)+(4,5,6)=(5,7,9)
所以(-3,6,-3).(5,7,9)=0
(a1,a2,a3)×(b1,b2,b3)=(a2b3-a3b2,a3b1-a1b3,a1b2-a2b1)
因为(1,2,3)x(4,5,6)=(2*6-3*5,3*4-1*6,1*5-2*4)=(-3,6,-3)
(1,2,3)+(4,5,6)=(5,7,9)
所以(-3,6,-3).(5,7,9)=0