ABSTRACT
Let’s look at a square of side-length 1. There are six straight lines that connect any two vertices of the square. The length of these lines is either https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429258992/853d5a60-735b-45bf-81d9-c2a4ec922025/content/figpg1_1.tif"/>
AB = BC = CD = DA = 1
or
AC = BD= √2.
