向量内积计算方法(向量内积计算)
1.(a+b)*(a-2b) =a^2-a*b-2b^2 =9-3*4/2-32 =-29. |a-b|^2=a^2-2a*b+b^2 =9-2*3*4/2+16 =13, |a-b|=√13. 2.向量AB*AC=6*7*cos150° =-21√3.。
1.(a+b)*(a-2b) =a^2-a*b-2b^2 =9-3*4/2-32 =-29. |a-b|^2=a^2-2a*b+b^2 =9-2*3*4/2+16 =13, |a-b|=√13. 2.向量AB*AC=6*7*cos150° =-21√3.。