由轨迹的条件求轨迹的极坐标方程,变化较多,学生不易掌握,而且求轨迹的极坐标方程还需要用到有关的三角知识,比之求轨迹的直角坐标方程要难一些;因此求轨迹的极坐标方程是解析几何教学中的一个难点。例如,在上海市平面解析几何课本中极坐标部份有这样一道题 The polar equation of the trajectory is obtained from the conditions of the trajectory, and the change is more difficult for the students to master. Moreover, the polar equation of the trajectory needs to use the relevant trigonometric knowledge, which is more difficult than the Cartesian coordinate equation of the trajectory; therefore, the trajectory is sought. The polar coordinate equation is a difficult point in analytical geometry teaching. For example, there is such a question in the polar coordinate part of the Shanghai Planar Analytic Geometry textbook