在中学数学中,关于四边形内容的这一章系统性特别强,体现了几种四边形一般与特殊的辩证关系.掌握其中的思想方法,不仅对学习这一章的基础知识会带来方便,而且对于我们掌握解决一般问题的科学方法,具有积极的意义.一般四边形有以下两条性质:1.四边形的内角和等于360°.2.四边形 In middle school mathematics, the chapter on quadrilateral content is particularly systematic, embodying the general and special dialectical relationships between several quadrilaterals. Grasping the ideas and methods in them not only facilitates learning the basics of this chapter, but also It is of positive significance for us to master the scientific methods for solving general problems. The general quadrangle has the following two properties: 1. The internal angle of a quadrilateral equals 360°. 2. Quadrilateral