设弦与双曲线的交点是A（x1.y1),B(x2,y2)那么x1+x2=2*3=6,y1+y2=2*(-1)=-2x1^2/4-y1^2=1x2^2/4-y2^2=1相减得：（x1+x2)(x1-x2)/4-(y1+y2)(y1-y2)=06(x1-x2)/4=-2(y1-y2)所以,弦的斜率k=(y1-y2)/(x1-x2)=-3/4所以,方...