矢量与标量乘积 aA=aAe+aAer+aA3 e3 a(A+B=aA+ab >矢量点乘 A·B=A1B1+A2B2+A3B3 A B=aRcos e A·B=B B (B+C)=A B+A C A= A➢ 矢量与标量乘积 ➢ 矢量点乘 a A B aA aB ( ) + = + 1 1 2 2 3 3 aA aA e aA e aA e = + + A B A B A B A B 1 1 2 2 3 3  = + + A B B A  =  A B C A B A C  + =  +  ( ) 2 A A A  = A B AB  = cos A B 