Answer
$ A(shaded) = 36 \pi - 54 \sqrt3$
Work Step by Step
Solving for the area of the circle is elementary:
$A= \pi r^2 = 36 \pi$
We also know that the area of the hexagon is:
$A = 3 \sqrt 3 /2(6^2)$
This gives:
$ A(shaded) = 36 \pi - 54 \sqrt3$