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笔者曾在文[1]中给出抛物线到圆锥曲线的如下一个变换(文[1]中的定理5):设抛物线C:y2=2px(p0),PQ是C的垂直于x轴的一条动弦,M(m,0),N(n,0)是x轴上的两个定点,则直线PM与NQ交点R的轨迹:(1)当m+n=0(m≠0)时为C;(2)当m+n0时为椭圆或圆;(3)当m+n0时为双曲线.下面,我们再给出抛物
The author has given the following transformation of a parabolic curve to a conic curve in [1] (Theorem 5 in [1]): Let parabola C: y2 = 2px (p0), PQ be a perpendicular line of C (M, 0) and N (n, 0) are the two fixed points on the x-axis, then the trajectory of the intersection point R of the straight line PM and NQ: (1) When m + n = 0 Is C; (2) oval or circle when m + n0; (3) hyperbolic when m + n0. Next, we give parabolic