What is the area of a circle with a circumference of 45m

The formula for the area is: A = pi * r²

Where r is the radius, and pi i the mathematical constant ≈ 3.14

 

And for the circumference: C = 2 * pi * r      =>      r = C/(2 * pi)

 

We combine the two formulas: A = pi * r² = pi * [ C/(2 * pi) ]² = pi * ( C²/4pi² )

 

A = C²pi/4pi²

 

A = C²/4pi

 

Now you just fill in for C = 45 m and pi ≈ 3.14