Area of a circle = PI x R^2
r = 1/2 diameter
r = 21.5/2
r = 10.75
Area of circle = 3.14 x 10.75^2 = 3.14 x 115.5625 = 362.86625 square units.
A semicircle is half a circle:
Area of semicircle = 362.86625 / 2 = 181.433125 square units (round the answer as needed).
