Everyone learns the number one rule about triangles in high school: the angles of a triangle add up to 180 degrees. But did you know that sometimes they don't? Triangles are much more interesting than ...

Earlier today I set you these mind-mangling puzzles about non-Euclidean geometry, in which the internal angles of triangles do not add up to 180 degrees. 1. Right, Right, Right. Assume the Earth is a ...