i am no good either but isnt the area of the semi circle AD = 4.5 pi as the area of circle = pi x r^2
semi circle is half that?
using chokes method,
let distance AD = 12, therefore AB, BC, CD = 4
Area of semi circle AD = 18pi (26pi/2)
Area of semi circle AB = 2pi (4pi/2)
Area of Semi circle...