高中数学　平面向量点击放大
点击放大
B(x,y),向量AB=(x-1)i+(y+2)j 向量AB与a=(2,3)同向: (x-1)/2 =(y+2)/3 ...(1) |AB| =根号[(x-1)^2+(y+2)^2] =2*根号13 ...(2) (1)(2)==> x=5,y=4, 点B(5,4)