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