5
Answer: ASet 2: Circles (Intermediate)
Explanation
PROBLEM
A circle has circumference 18pi. What is its radius?
A circle has circumference 18pi. What is its radius?
A.✓ Correct
9
B.
18
C.
8
D.
7
Detailed Explanation
Choice A is the best answer. C = 2 times pi times r. 18pi = 2 times pi times r. r = 9
Why others are wrong:
B: 18 is incorrect because it does not satisfy the equation.
C: 8 is incorrect because it does not satisfy the equation.
D: 7 is incorrect because it does not satisfy the equation.