中点,这在平面几何中是经常出现的。现行中学教材中对几何变换的思想已略有渗透。本文首先阐述中心对称变换的一个基本性质。然后通过若干例子说明用中心对称变換的方法处理平面几何中与中点有关的问题的简便性。定义如果平面到其自身的一个映射,使任意一对对应点A、A′的连线段都通过一个定点O,且被这一点所平分,则这个映射叫做中心对称变换(亦称点 The midpoint, which is often seen in plane geometry. The idea of ​​geometric transformation in the current middle school textbooks has slightly penetrated. This article first describes a basic property of the central symmetry transformation. Then, the simplicity of the problem related to the midpoint in plane geometry is illustrated by several examples. Defining a mapping from a plane to itself such that any pair of segments of the corresponding points A, A’ passes through a fixed point O and is equally divided by this point, the mapping is called a centrosymmetric transformation (also known as a point