解析几何中的最值问题,以直线和圆锥曲线为背景,以函数、不等式和导数等知识作工具,有较强的综合性.同时,这类问题没有固定的模式,解法灵活,对能力要求较高,是高中数学竞赛中的难点内容.处理解几中的最值问题,常用的方法有:函数法、方程法、几何法、参数法等.图1例1图例1(1999 Analyze the most value problem in geometry, take the straight line and the conic as the background, and use the knowledge of function, inequality and derivative as the tools, and have strong comprehensiveness. At the same time, there is no fixed mode of such problems, and the solution is flexible. Higher, is the difficulty of high school mathematics contest content. Solutions to solve the most value problems, commonly used methods are: function method, equation method, geometry method, parameter method, etc. Figure 1 Example 1 Figure 1 (1999