Centre angle will be 360° as its totally a circle.
Angle between two cars=360/20=18°
[tex]\\ \sf\longmapsto L=\dfrac{\theta}{360}(2\pi r)[/tex]
[tex]\\ \sf\longmapsto L=\dfrac{18}{360}(2\pi(25))[/tex]
[tex]\\ \sf\longmapsto L=\dfrac{1}{20}(50\pi)[/tex]
[tex]\\ \sf\longmapsto L=2.5\pi ft[/tex]
Now
Area be A
[tex]\\ \sf\longmapsto A=\dfrac{1}{2}Lr^2[/tex]
[tex]\\ \sf\longmapsto A=\dfrac{1}{2}(2.5\pi)(25)^2[/tex]
[tex]\\ \sf\longmapsto A=625(2.5)\pi\dfrac{1}{2}[/tex]
[tex]\\ \sf\longmapsto A=1562.5\pi/2[/tex]
[tex]\\ \sf\longmapsto A=781\pi ft^2=[/tex]