Why is pi here? And why is it squared? A geometric answer to the Basel problem

A most beautiful proof of the Basel problem, using light. Help fund future projects: An equally valuable form of support is to simply share some of the videos. Special thanks to these supporters: This video was sponsored by Brilliant: Brilliant’s principles list that I referenced: Get early access and more through Patreon: The content here was based on a paper by Johan Wästlund ~wastlund/ Check out Mathologer’s video on the many cousins of the Pythagorean theorem: On the topic of Mathologer, he also has a nice video about the Basel problem: A simple Geogebra to play around with the Inverse Pythagorean Theorem argument shown here. Some of you may be concerned about the final step here where we said the circle approaches a line