类比点与圆的位置关系的有关结论,我们容易知道,点P(x0,y0)在椭圆内部的充要条件是:(若把不等号改为相反的方向,则为点P在椭圆外部的充要条件,证明从略).应用这一结论,可使许多问题的解答简捷、巧妙.下面从五个方面说明这一 We can easily know that the point P(x0,y0) in the interior of the ellipse is a necessary and sufficient condition for the positional relationship between the analogy point and the circle: (if the inequality is changed to the opposite direction, the point P is outside the ellipse If conditions are to be used, the proof may be abbreviated. Applying this conclusion can make the answers to many questions simple and ingenious. Here are five ways to illustrate this.