6. The length of side $A D$ of the inscribed quadrilateral $A B C D$ is 6. Point $M$ divides this side in the ratio $A M: M D=1: 5$, and the lines $M C$ and $M B$ are parallel to the sides $A B$ and $C D$ respectively. Find the length of side $B C$ of the quadrilateral.
Answer: $BC=\sqrt{5}$.

## Grading Criteria for the ON-SITE Final Round of the Rosatom Olympiad 2023 for 11th Grade

In all problems, the correct answer without justification is 0