IMSO 2017 — Mathematics — Essay Question 7

Square $ABCD$ has sides of length 12 cm. The centre of the square is $O$, and $P$, $Q$, $R$ and $S$ are the midpoints of $OA$, $OB$, $OC$ and $OD$ respectively. Find the area, in $\mathrm{cm}^2$, of the shaded region.