MathDB

Let

ABCD

be a square with side length

2015

. A disk with unit radius is packed neatly inside corner

A

(i.e. tangent to both

\overline{AB}

and

\overline{AD}

). Alice kicks the disk, which bounces off

\overline{CD}

\overline{BC}

\overline{AB}

\overline{DA}

\overline{DC}

in that order, before landing neatly into corner

B

. What is the total distance the center of the disk travelled?
Proposed by Evan Chen

Problem Statement