In a plane, turning a figure around a point by an angle in a certain direction is called the rotation of the figure. This fixed point is called the center of rotation and the rotation angle is called the rotation angle.

The rotation of a figure means that each point on the figure moves around a fixed point on the plane at a fixed angle, in which the distance from the corresponding point to the rotation center is equal, the length of the corresponding line segment is equal to the size of the corresponding angle, and the size and shape of the figure have not changed before and after rotation.