所谓旋转法,就是固定一点或一条直线,把图形的其他部分绕该点或该轴旋转到另一位置,使有关的元素集合在一起,以利找出解题途径.这种方法,从本质上讲,就是作等形变换;在应用上,具有广泛而灵巧的特征;在作法上,往往要借助于相等线段和相等角度;在思维上,能发展学生的空间想象力.但是,学生对这种方法是不熟悉的.虽然他们在学习全等三角形和旋转体时迂到过,却很少做这方面的练习,因此有加强教学的必要. The so-called rotation method is to fix a point or a straight line, rotate the other part of the figure around the point or the axis to another position, so that the relevant elements are grouped together to help find the solution to the problem. This method, from the essence In terms of application, there is a wide range of dexterous features; in practice, it is often necessary to resort to equal line segments and equal angles; in thinking, students can develop spatial imagination. However, students This method is unfamiliar. Although they have learned to learn full triangles and rotating bodies, they rarely do exercises in this area. Therefore, it is necessary to strengthen teaching.