Descartes' theorem

Descartes' Theorem says that if you draw any four (4) straight lines so that they all cross each other at the same point (called an intersection point), then the lines will all be the same distance apart from each other. So it's like if you have four (4) rulers and you put them all together in a pointy shape, with all of the rulers touching the same spot, you'll have a perfect square – every side has the same length.