在平面几何证明点的共圆问题中,最常见的是证明四点共圆。在证题中还可运用四点共圆的知识再去论证其它问题。证明四点共圆一般有六种情况:(一)依据圆的定义,证明要证共圆的四点距离某一定点等远。例1.已知 BD、CE 分别是△ABC 的边 AC、AB 上的高,求证:B、C、D、E In the plane of geometric proof of the total point of the problem, the most common is to prove the four-point total circle. You can also use the four-point total knowledge in the title to prove other issues. There are generally six cases of four-point co-ordination. (A) According to the definition of a circle, it is proved that a total of four points of a total number of points must be farther away from a given point. Example 1. Known BD, CE are △ ABC side AC, AB on the high, verify: B, C, D, E