Answer
$\approx 219,911 ft^{2}$
Work Step by Step
To convert into radians, multiply the angle by $\pi/180^{o}$.
$\displaystyle \theta=280^{o}\cdot\frac{\pi}{180^{o}}$ rad$=\displaystyle \frac{14\pi}{9}$ rad
The area $A$ of a sector with central angle of $\theta$ radians is
$ A=\displaystyle \frac{1}{2}r^{2}\theta$.
$ A=\displaystyle \frac{1}{2}\cdot 300^{2}\cdot\frac{14\pi}{9}\approx$219911.485751
$\approx 219,911 ft^{2}$
