For this case we have to:
If Sergio has 72 feet of fence then we have that the circumference of the fence (whose space is circular) is 72.
By definition, the circumference of a circle is given by:
![C = \pi * d](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8sedh4dd0xvka1zi6kuzjhwtedl5y34sgp.png)
Where:
d: It is the diameter of the circumference
So:
![72 = \pi * d\\d = \frac {72} {\pi}\\d = \frac {72} {3.14}\\d = 22.93 \ ft](https://img.qammunity.org/2020/formulas/mathematics/high-school/4q31h9nfiutoyka28bddx0iuf6orvqg9i2.png)
Then, the radius will be given by: r = 11.45 \ ft
Thus, the area of the circular portion will be:
![A = \pi * r ^ 2\\A = 3.14 * (11.45) ^ 2\\A = 3.14 * 131.1025\\A = 411.66 \ ft ^ 2](https://img.qammunity.org/2020/formulas/mathematics/high-school/n9zdzcc5yp3miuj2kmgeeyfx6rl5ecxlgi.png)
Thus, the area of the playing space is:
![A = 411.66 \ ft ^ 2](https://img.qammunity.org/2020/formulas/mathematics/high-school/ofie6h1qra95u307yr2jk5zjad3tywztju.png)
Answer:
![A = 411.66 \ ft ^ 2](https://img.qammunity.org/2020/formulas/mathematics/high-school/ofie6h1qra95u307yr2jk5zjad3tywztju.png)