Problem

Source: 2020 Instagram Math Olympiad R1 p4 IGMO

Tags: combinatorics, combinatorial geometry



Three frogs are initially on the vertices of an equilateral triangle with sides length of $1$. The frogs can jump over each other in the following way: if frog $A$ at point $M$ jumps over frog $B$ at point $N$, then frog $A$ will land on point $O$ such that $MN = ON$ and $M, N, O$ are collinear. By repeated jumping, is it possible that the three frogs eventually move to the vertices of an equilateral triangle with sides length of $10$?