Answer:
- circumference: 62.8 ft
- area: 314 ft²
Explanation:
The circumference is given by the formula ...
 C = πd
Using the given numbers, the circumference is ...
 C = (3.14)(20 ft) = 62.8 ft
__
The area is given by the formula ...
 A = πr² . . . . . where radius r is half the diameter
Using the given numbers, the area is ...
 A = 3.14(10 ft)² = 314 ft²