In order to find the radius of the circle use the following formula for the area of a piece of circle with a given central angle:
[tex]A=\frac{\theta}{360}\pi r^2[/tex]in this case you have:
A = 20 ft²
θ = 40°
r = ?
first, solve for r in the given formula and then replace the value of A:
[tex]\begin{gathered} r=\sqrt[]{\frac{360}{\theta\pi}A} \\ r=\sqrt[]{\frac{360}{40\pi}(20)}ft\approx7.6ft \end{gathered}[/tex]Hence, the radius of th cricle is r = 7.6 ft
