To solve this problem you must apply the proccedure shown below:
1. You must apply the formula for calculate the area of a circle, which is:
A=πr^2
Where A is the area of the circle and r is the radius of the circle.
2. You have that the diameter is 6 feet, then the radius is:
r=D/2
r=3 feet
3. When you apply the formula shown above, you obtain:
A=9π feet^2
A=28.27 feet^2
The answer is: 28.27 feet^2