四边形是人们生活中常见的一种几何图形,在日常生活或生产实践中具有很广泛的应用,其包含平行四边形、矩形、菱形、正方形与梯形等特殊四边形,既是基本的几何图形,也是初中“几何与图形”的主干知识,它是几何知识在三角形上的拓展与延伸,是学习相似形、圆等知识的基础.一、教材关于“四边形”的处理“四边形”的重点是平行四边形的定义、性质与判 Quadrilateral is a kind of common geometry in people’s life. It is widely used in daily life or production practice. It contains special quadrangles such as parallelogram, rectangle, rhombus, square and trapezoid. It is not only the basic geometry but also the junior middle school The main knowledge of “Geometry and Graphics”, which is the expansion and extension of the geometric knowledge on the triangle, is the basis for learning the similarities, circles, etc .. First, the teaching material on the “quadrilateral” processing “quadrilateral” The focus is on the definition, nature and adjudication of parallelograms