Respuesta :

The formula of the area of a circle is

[tex]A=\pi r^2[/tex]

where r is the radius

in this case, we have the length of the diameter, the diameter is twice the radius

d= diameter

d=2r

therefore

r=d/2

r=8/2

r=4

we substitute the value of the radius in the formula

[tex]A=\pi r^2=\pi(4)^2=16\pi=50.27\operatorname{km}^2[/tex]

the area of a circle with a diameter of 8km is 16pi km^2 or 50.27km^2