已知圆锥曲线 C 上存在关于直线 l_m 对称的两点,求参数 m 的取值范围及有关问题,这类题在近年的高考题中屡屡出现,解法甚多,本文介绍用极坐标求解的方法. It is known that there are two points symmetrical about the line l_m on the conic curve C. Find the range and related problems of the parameter m. Such questions have appeared frequently in the college entrance examination questions in recent years and many solutions have been made. This article describes the method of solving with polar coordinates. .