圆锥曲线的定义在处理与平面几何知识相结合的有关问题时发挥着至关重要的作用.充分利用圆锥曲线的定义及数形结合、转化思想来解题,是解决此类题目的通法.一、椭圆1.椭圆第一定义的应用例1点F为椭圆x2/a2+y2/b2=1(a>b>0)的一个焦点,若椭圆上存在点A,使AOF为正三角形,则椭圆的离心率为() The definition of conic is playing a crucial role in dealing with the related problems of plane geometry knowledge.Taking full advantage of the definition of conic and the combination of number and shape, transformation thinking to solve problems is the way to solve such problems. First, the ellipses 1. Ellipse The first definition of the application of Example 1 point F is an ellipse x2 / a2 + y2 / b2 = 1 (a> b> 0) of a focus, if there is a point on the ellipse, so  AOF is a regular triangle , Then the elliptical eccentricity ()