Desargues定理及其逆定理的应用推广

Popularization on Application of Desargues Theorem and its Inverse

Desargues定理及其逆定理揭示了在两个三点形(初等几何中称为三角形)中存在着一种很重要的位置关系,因此,在证明初等几何中一些有关"点共线"或"线共点"的定理或命题时,常常用到它们.在应用Desargues定理(或其逆定理)时,其关键就在于正确确定两个满足定理条件且符合所证命题结论的三点形来.当然,这两个三点形有时并不是唯一的一对,可根据实际情况灵活地加以选用.

The theorem and its inverse revealed in the form of two three o＇clock（elementary geometry as triangles） and there is a very important position in relationship,therefore,in proving some of the elementary geometry ＂point total of line＂ or ＂ Line total point ＂theorem or proposition,it is often used them.In the application of Theorem（or its inverse）,the right to determine the key lies in two theorems satisfy the conditions and comply with the form of certificates to the three propositions conclusions.Of course,this is not the only two point-shaped and sometimes a pair,according to the actual situation to be used flexibly.