性质一对于圆锥曲线mx2+ny2=1(mn≠0)的内接四边形的两组对边、两条对角线所在的三对直线中,只要其中有一对直线的斜率之和为0,则另两对直线中的每一对直线的斜率之和也为0.证明设A(x1,y1),B(x2,y2),C(x3,y3),D(x4,y4)为圆锥曲线mx2+ny2=1(mn≠0)的内接四边形的四个顶点,由字母A、B、C、D的轮换 For one pair of two sides of the inscribed quadrilateral with conic mx2 + ny2 = 1 (mn ≠ 0), if the sum of the slopes of one pair of straight lines is 0 among the three pairs of straight lines where the two diagonals are, then The sum of the slopes of each of the other two pairs of straight lines is also 0. It is proved that A (x1, y1), B (x2, y2), C (x3, y3), D (x4, y4) The four vertices of the inscribed quadrilaterals of mx2 + ny2 = 1 (mn ≠ 0), rotated by the letters A, B, C, D