Half of a Page

Simon Gregg was planning a lesson out loud, that started with a Graham Fletcher 3 Act which involves cutting a rectangle out of a piece of paper and asking which is bigger. Spoiler: they are equal. Which got me thinking about cutting out such things. Which got me thinking about how far the first corner of the cut rectangle could go... which wound up with this sketch. What is the type or equation of the boundary curve? Simon's post: http://followinglearning.blogspot.fr/2016/01/the-l-shaped-room.html Graham's 3 act: http://gfletchy.com/paper-cut/