An icon in the shape of a lightning bolt. Impact Link 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 ...

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 ...

Euclid’s Elements, which presented the state of the art in geometry around 300 B.C., has been extraordinarily influential. This massive, 13-volume compendium set the standard for mathematical ...

The ancient Greek geometer Euclid presented a list of five axioms he held to be self-evidently true. They are (or are equivalent to): You can draw a line between any two points. You can extend lines ...