2. c 270
3.d. Two times r equals the diameter of the circle. Pi equals the circumference divided by the diameter. When you multiply, the diameter is in both the numerator and the denominator, which cancels out, leaving the circumference.
4. c 155
5. c 70
6.b 55
7. c 19 in
8. a 183.3 ft
9. b 8 pi ft
10. b 33 pi in
