Inverse Pythagorean Theorem

Source 1 Mathologer
403: Invalid response for http://www.youtube.com/oembed?format=json&maxwidth=620&maxheight=300&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dp-0SOWbzUYI
source 2: 3Blue1Brown in The stunning geometry behind this surprising equation (the Basel problem)
403: Invalid response for http://www.youtube.com/oembed?format=json&maxwidth=620&maxheight=300&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3Dd-o3eB9sfls
– ortollj

Information: Inverse Pythagorean Theorem