Given:
Semi-circle
bottom is 36 inches
The bottom is the diameter of the circle. Radius of the circle is 1/2 of diameter.
r = 36incehes / 2 = 18 inches
Area of a circle = π r²
A = 3.14 * (18in)²
A = 3.14 * 324in²
A = 1,017.36 in²
Area of a semi-circle = Area of a circle ÷ 2
A = 1,017.36 in² ÷ 2
A = 508.68 in²