Every smooth Jordan curve has an inscribed rectangle with aspect ratio equal to $\sqrt{3}$

Abstract

We use Batson's lower bound on the nonorientable slice genus of $(2n,2n-1)$-torus knots to prove that for any $n\ge 2$, every smooth Jordan curve has an inscribed rectangle of of aspect ratio $\tan (\frac{\pi k}{2n})$ for some $k\in \{1,...,n-1\}$. Setting $n=3$, we have that every smooth Jordan curve has an inscribed rectangle of aspect ratio $\sqrt{3}$.