This open problem taught me what topology is

The inscribed square/rectangle problem, solved using Möbius strips and Klein bottles. Playlist with more neat proofs: https://www.youtube.com/playlist?list=PLZHQObOWTQDPSKntUcMArGheySM4gL7wS Instead of sponsored ad reads, these lessons are funded directly by viewers: https://3b1b.co/support An equally valuable form of support is to simply share the videos. This argument was originally by Herbert