2024 USAJMO Problems

Revision as of 21:26, 19 March 2024 by Ryanjwang (talk | contribs) (Day 1)

Day 1

Problem 1

Let $ABCD$ be a cyclic quadrilateral with $AB=7$ and $CD=8$. Points $P$ and $Q$ are selected on line segment $AB$ so that $AP=BQ=3$. Points $R$ and $S$ are selected on line segment $CD$ so that $CR=DS=2$. Prove that $PQRS$ is a quadrilateral

Problem 2

Let $m$ and $n$ be positive integers. Let $S$ be the set of integer points $(x,y)$ with $1\leq x\leq2m$ and $1\leq y\leq2n$. A configuration of $mn$ rectangles is called happy uf each point in $S$ is a vertex of exactly one rectangle, and all rectangles have sides parallel to the coordinate axes. Prove that the number of happy configurations is odd.