If you fold along the x axis, the x coordinate remains unchanged and the y coordinate becomes the reciprocal of the original coordinate.

If you fold along the y axis, the y coordinate remains unchanged and the x coordinate becomes the reciprocal of the original coordinate.

If it is symmetrical along a straight line, this is the content of high school, and there will be no mid-term exam. Just remember the above two points.

For example, it is known that A( 1, 1) B(2,1) C (3,4) finds the triangle three-point coordinates obtained by folding the triangle ABC along the X axis.

The solutions correspond to ABC (1,-1) (2,-1)(3, -4) respectively.