How to Reflect a Figure over a Line with a Compass
To reflect a figure about a line, you must move all the points on one side of the line to the other side. This should work in the same way as your reflected image does when you look in a mirror.
You can accomplish this in a very tiresome way—by moving every single point. Or, you can be a little smarter, and move strategic points, most often corners, so you can then draw the lines between them. Below are instructions for how to proceed.
Rule
The figure shows a reflection of the line on the line :