It's actually very simple. Semicircle is a half of a circle. So the area and perimeter is also divided by 2. Also the radius is a half of diameter so 130.
[tex]Area=\frac{\pi130^2}{2}\approx\frac{53092.92}{2}=\boxed{26546.46ft^2}[/tex]
Hope this helps.
r3t40
