The Challenge: Pick YOUR favorite proof, or mathematical fact and illustrate it. What’s beautiful about it? Why do you love it? I really, truly want to know.

And it doesn’t have to be fancy. It can be simple. The runner up for me is probably the triangle area formula. The following, however has to be the winner as even ~10 years after I learned it, if I’m reminded of it, it still stops me in my tracks.

MY favorite proof, and still, to this day, the most beautiful thing I think I’ve ever experienced in mathematics, is a proof for how many spaces are created by n-crossing lines. If you just want the prettier part, here you are. This is the proof:

Here’s even a time lapse:

But (insert math teacher persona here) the REAL beauty is, of course, the idea. Which I did my best to explain here: