12.56
615.75
3.14159265 square feet.
63.6173 ft2
None. A 12 foot diameter is the length across a circle: it is a linear distance, not an area.
2512
450
132.73
346
1590.4
176.625
12.56
615.75
153.93804 square feet.
3.14159265 square feet.
A circle with a diameter of 18 feet has an area of 254.5 square feet.
A circle with a diameter of 24 feet has an area of 452 square feet.