What's the circumference and area of a circle with a radius of 9 km

Area = pi*r^2

Area = 81*pi km^2 or about 254.34 km^2

Circumference=2*pi*r

Circumference = 18*pi km or about 56.52 km

The formula of circumference for a circle is ((or 3.14) {pie}) * (d (or 2 radius))

The formula for area for a circle is {pie}*r^2

That way ...

9*2=18*3.14 (shortcut for pie) = 56.52

So out circumference would be 56.52km^2

Area

9^2=81*3.14=254.34

So our area would be 254.34 km^2