切点弦的问题是圆锥曲线中的重要内容之一,是近几年高考的热点考题,切点弦涉及到的问题,难度较大,技巧性强,计算繁琐,学生遇到此类问题较为棘手,束手无策,这里通过类比推理,探究其规律,掌握其性质,触类旁通,化繁就简,降低难度,进一步提高学习效率.一、圆的切线和切点弦方程 The problem of tangent point chord is one of the important contents in the conic curve. It is a hot topic in the college entrance examination in recent years. The problems involved in tangent chord are more difficult, more skillful and complicated to calculate. Students encounter such problems Thorny, helpless, here by analogy, to explore its laws, to grasp its nature, touch analogy, simplification, reduce difficulty and further improve the learning efficiency. A round tangent and tangent chord equation