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

Opposite angles in a cyclic quadrilateral add up to 180°

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