所谓旋转问题,即指把一个几何图形,按照一定方式旋转,使得新旧图形的各边角之间构成位置关系,从而得到相应的几何问题。解此类题的关键是抓住其旋转中心或旋转轴,利用旋转角,全等三角形,扇形的弧长,面积计算等等知识来解题。 The so-called rotation problem means that a geometrical figure is rotated in a certain way so that the corners of the old and new figures form a positional relationship, and corresponding geometric problems are obtained. The key to solving such a problem is to grasp its rotation center or rotation axis, and use the knowledge of rotation angle, congruent triangle, fan arc length, area calculation and so on to solve the problem.