China2009的个人空间

如圆锥曲线的例六过M(1,1)的直线交x^2/4-y^2/2=1于A,B,若M为AB中点，求直线AB方程利用对称性解设A(x,y),则B(2-x,2-y)...得x-2y+1=0之后为什么还要设B(x,y),则A(2-x,2-y)...得x-2y+1=0...设A(x,y),则B...