(本讲适合初中 )1　基础知识对称变换是将平面图形Ｆ1变到与它轴对称的图形Ｆ2 .对称变换也是一种合同变换 ,并且对称点的连线被对称轴垂直平分 .应用对称变换解几何题时 ,常见的基本思路是 :如果图形是轴对称图形 ,则经常要添设对称轴以便充分利用轴对称图形的性质 ;如果图形 (This lecture is suitable for junior high school.) 1 Fundamental Knowledge Symmetrical transformation is to change the plane graph F1 to a graph F2 symmetrical to its axis. The symmetry transformation is also a kind of contract transformation, and the line of symmetry points is vertically bisected by the axis of symmetry. The symmetry transformation solution is applied. In geometry problems, the common basic idea is: if the graph is an axisymmetric graph, it is often necessary to add an axis of symmetry in order to take full advantage of the nature of the axisymmetric graph; if the graph