旋转的特征之一是旋转前后的图形全等,因此图形旋转变换的作用在于通过边角之间的等量代换,将分散的边、角集中,构造新图形,为证明线段与角的相等、和、差、倍分关系作铺垫.利用旋转作辅助线的关键是理清选哪个点为旋转点,旋转哪一部分图形,旋转多少度,按什么方向旋转,称之为旋转四部曲。下面,我们通过对典型例题的分析,归纳总结旋转作辅助线的几何模型. Rotation is one of the characteristics of the rotation before and after the congruent graphics, so the role of graphics rotation transform is equivalent to the corner between the substitutions, the scattered edges and corners to construct a new graphics, in order to prove that the line segment and angle equal , And, poor, multiplier relationship to pave the way for the use of rotation as the auxiliary line is to sort out the key point is to clarify the point of rotation, which part of the rotation graphics, how many degrees of rotation, according to what direction rotation, called the rotation of the four. Below, we analyze the typical examples, summarize the geometry of the rotation as a guideline.