Answer
$A=36\pi-72$ sq.units
Work Step by Step
The diagonal of the square equals the diameter of the circle.
From the equation, r=6, diameter = 12
The sides a of the square and the diagonal d satisfy Pythagorean theorem
$a^{2}+a^{2}=d^{2}$
$2a^{2}=12^{2}$
$a^{2}=\displaystyle \frac{144}{2}=72$
$a^{2}$ is the area of the square....
$A_{sq}=72$ sq.units
This area is subtracted from the area of the circle,
$A=A_{circ}-A_{sq}$
$A=6^{2}\pi-72$
$A=36\pi-72$ sq.units
