学立体几何首先学习的是平面性质的三个公理及其推论.多数同学感觉到这三个公理很简单,但是却不知道如何去应用,说明对基础知识理解不透.针对这一情况,本文对这三个公理的理解、应用等方面加以说明,以期对同学们有所帮助. The first step in learning three-dimensional geometry is to learn the three axioms of planar nature and its inferences. Most students feel that these three axioms are very simple, but they do not know how to apply them, which means that they cannot understand the basic knowledge. For this situation, this article The explanations and applications of these three axioms are explained in order to help the students.