Solid line. Rotation does not change the shape and size of the graph. After the figure is rotated, the corresponding line segments are equal, the corresponding angles are equal, and the line segments connected by the corresponding points are equal. It can be considered as the result of adding the same vector to each point or moving the center of the coordinate system. Mathematics is a universal means for human beings to strictly describe abstract structures and patterns of things. Mathematics is a subject that studies concepts such as quantity, structure, change, space and information.