Every polygon can be triangulated into exactly n-2 triangles. So you’ve got the triangulation theorem and the totally opposite theorem in the math universe, Girard’s theorem (the formula for the era of a spherical triangle). I’m going to attempt to put these two together to prove Euler’s polyhedral formula (also known as Euler’s characteristic) V – E + F = 2.

A week later Simon and a friend of his from Germany worked together for several hours, writing a program to cut polygons. It’s still unfinished but is already fun to play with: https://editor.p5js.org/simontiger/sketches/YxNUp5rdJ