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 equal...