Question 63
Given a line $\ell$ and four points $P$, $Q$, $R$ and $S$ (in that order) on the line, describe a straight edge (unmarked ruler) and compass construction producing a square $ABCD$ such that $P$ lies on the line $AD$, $Q$ on the line $BC$, $R$ on the line $AB$ and $S$ on the line $CD$.