Ptolemy’s Theorem and the Almagest: we just found the best visual proof in 2000 years

描述

We are making history again by presenting a new visual proof of the 2000+ years old Ptolemy's theorem and Ptolemy's inequality. 00:00 Introduction 04:27 Geometry 101 08:19 Applications 14:46 Ptolemy's inequality 18:34 LIES 25:35 Animated proofs 28:57 Thank you! 30:53 Degenerate Easter Egg There are some other proofs of Ptolemy's theorem/inequality based on scaling and aligning suitable triangles. However, none of them is as slick, beautiful and powerful as Rainer's new proof. In particular, check out the animated scaling proof on the wiki page for Ptolemy's theorem (and this https://youtu.b