I'm guessing you're saying that the sprinkler is shooting out 23 ft of water.
This would be the same as the radius of a circle, and we're trying to find the area. Use the formula.
[tex]\sf A=\pi r^2[/tex]
Plug in what we know:
[tex]\sf A=\pi (23^2)[/tex]
[tex]\sf A=529\pi ft^2[/tex]
This is what they could be looking for, an exact value. If they want an approximation, we can input 3.14 for Pi:
[tex]\sf A\approx 529(3.14)[/tex]
[tex]\boxed{\sf A\approx 1661.06~ft^2}[/tex]