The formula of the area of a semi circle is half the area of the circle
\(\frac{ \pi r^2}{2}\)
Diameter = 21 ft
Radius = \(\frac{d}{2}\) = \(\frac{21}{2}\) = 10.5 ft
Area = \(\frac{ \pi (10.5)^2}{2}\)
= \(\frac{110.25 \pi }{2}\)
=\(\frac{110.25 * 3.14}{2}\) (3.14 as \(\pi\))
=\(\frac{346.185}{2}\)
=173.0925 ft² ≈ 173.1 ft² ≈ 173 ft²
To the nearest square foot : 173 ft²
