Use pi=22/7.
The radius (r) of a circle is 1/2 the diameter = 1/2 * d.
The area of a circle is
A(square)=s*s.
For the given square that's
The grass is the A(square) - A(circle) = 8100-2376.79=5723.21 square feet.
Not sure what the problem indicated you should use as pi. The answer will be slightly different if 3.14159 is used.
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