Answer:
[tex]\huge\boxed{A_R=18\pi\ cm^2}[/tex]
Step-by-step explanation:
[tex]\dfrac{80^o}{360^o}=\dfrac{8}{36}=\dfrac{2}{9}[/tex]
The shaded region is 2/9 of whole circle.
Calculate the area of a circle:
[tex]A=\pi r^2[/tex]
[tex]r[/tex] - radius
Substitute [tex]r=9cm[/tex]
[tex]A_O=\pi\cdot9^2=81\pi(cm^2)[/tex]
Calculate the area of the shaded regions:
[tex]A_R=\dfrac{2}{9}A_O\\\\A_R=\dfrac{2}{9}\cdot81\pi=2\cdot9\pi=18\pi(cm^2)[/tex]
