At some point in your teenage years, you probably kept a compass and straightedge in your backpack, learned the ways to prove two triangles are congruent, and knew what a secant was. It all had a ...

We’ve all learned “parallel lines never intersect” in high school geometry. But what your teachers failed to explain is that “parallel lines never intersect” is only true in Euclidean geometry, which ...

IT is interesting to compare the attitudes of the two most recent writers in English who deal with Euclidean geometry. Sir Thomas Heath, in the second edition of his three-volume translation of the ...