The circumference of a circle is given by the formula:
[tex]C\text{ = }\pi\cdot\text{ D}[/tex]That is the number pi (3.141592....) times the diameter. Then, we have (for pi = 3.14):
[tex]C\text{ = 3.14 }\cdot\text{ 12 ft = 37.68 ft}[/tex]The circumference is 37.68ft.