对“对称性”的研究常常可以使我们加深对事物性质的认识,而图形的对称性是用对称变换来描述的,对称变换是保持图形不变的刚体运动,人教A版教材在附录中证明了有不动点的平面刚体运动只有旋转变换和反射变换.由这个结论可知,若一个图形的对称变换有不动点,那么它只能是旋转变换或 The study of “symmetry” often allows us to deepen our understanding of the nature of things. The symmetry of the graph is described by the symmetry transformation. The symmetry transformation is the rigid body motion that keeps the graph unchanged. The appendix shows that the plane rigid body motion with fixed points only has rotation transformation and reflection transformation. From this conclusion, if a symmetrical transformation of a graph has a fixed point, then it can only be a rotation transformation or