August 15, 2017 (8/15/17) was Pythagorean Theorem Day (see I missed Pythagorean Theorem Day). I was not even aware that there was such a day until this year, but it brought to my attention some really ...

Two years ago, a couple of high school classmates each composed a mathematical marvel, a trigonometric proof of the Pythagorean theorem. Now, they’re unveiling 10 more. For over 2,000 years, such ...