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

From Mathologer. 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…

Way beyond the golden ratio: The power of AB=A+B (Mathologer masterclass)

From Mathologer. Today’s mission: saving another incredible discovery from falling into oblivion: Steinbach’s amazing infinite family of counterparts of the golden ratio discovered around 1995. Lot’s of my own little discoveries in this one 🙂 00:00 Intro 05:53 Ptolemy 09:18 Perfect cut 16:01 Golden rectangle 22:03 Fibonacci 33:07 A+B=AB 45:48 Images and music 47:27 Thank…

Conway’s IRIS and the windscreen wiper theorem

From Mathologer. Conway’s whatever … it’s named after John Conway and so it must be good 🙂 Wiki page dedicated to John Conway https://en.wikipedia.org/wiki/John_Horton_Conway Wiki page Conway’s circle https://en.wikipedia.org/wiki/Conway_circle_theorem Wiki page on his Game of Life https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life Michael de Villiers (the connection with the windscreen wiper theorem, read this one first) http://dynamicmathematicslearning.com/conway-circle-theorem-special-case-side-divider-theorem.pdf http://dynamicmathematicslearning.com/conway-circle-as-special-side-divider-theorem.html Also check…

Simple yet 5000 years missed ?

From Mathologer. Good news! You really can still discover new beautiful maths without being a PhD mathematician. Stumbled across this one while working on the magic squares video. Another curious discovery by recreational mathematician Lee Sallows. A simple and beautiful and curious fact about triangles that, it appears, was first discovered only 10 years ago.…

What’s the curse of the Schwarz lantern?

From Mathologer. Second coop with Andrew. This time it’s about the Schwarz lantern a very famous counterexample to something that mathematicians believed to be obviously true. A 3D cousin of the famous pi = 4 paradox. 00:00 Intro 00:39 Troll math: the pi=4 meme 02:25 Archimedes chops off corners 05:51 Archimedes boxing of pi 07:40…

The best A – A ≠ 0 paradox

From Mathologer. This video is about a new stunning visual resolution of a very pretty and important paradox that I stumbled across while I was preparing the last video on logarithms. 00:00 Intro 00:56 Paradox 03:52 Visual sum = ln(2) 07:58 Pi 11:00 Gelfond’s number 14:22 Pi exactly 17:35 Riemann’s rearrangement theorem 22:40 Thanks! Riemann…

Powell’s Pi Paradox: the genius 14th century Indian solution

From Mathologer. Around 1400 there lived an Indian astronomer and mathematician by the name of Madhava of Saṅgamagrāma. He was the greatest mathematician of his time and, among other mathematical feats, he and his followers managed to discover a lot of calculus 200 years before Newton and Leibniz did their thing. While preparing a video…

Fibonacci = Pythagoras: Help save a beautiful discovery from oblivion

From Mathologer. In 2007 a simple beautiful connection Pythagorean triples and the Fibonacci sequence was discovered. This video is about popularising this connection which previously went largely unnoticed. 00:00 Intro 07:07 Pythagorean triple tree 13:44 Pythagoras’s other tree 16:02 Feuerbach miracle 24:28 Life lesson 26:10 The families of Plato, Fermat and Pythagoras 30:45 Euclid’s Elements…