You can do it; it's easy.
Dunno if this is correct:
We know the perimeter of a circle (or circumference) is \(2\pi R\). So that means if we want to find the area of a semi-circle, we have to divide the perimeter by 2:
Radius (R) = 5.
So it's 2 * 3.142 * 5 = 31.42.
We have to divide this by 2 so we can get our final answer:
31.42 / 2 = 15.71.
Ahh I noticed why mine was incorrect, I only did the curvy side and forgot about the bottom:
15.71 + 10 = 25.71