1
Answer: BSet 2: Circles (Beginner)
Explanation
PROBLEM
A circle has radius 9. What is its circumference? (Express answer as a number times pi)
A circle has radius 9. What is its circumference? (Express answer as a number times pi)
A.
81pi
B.✓ Correct
18pi
C.
9pi
D.
20pi
Detailed Explanation
Choice B is the best answer. Circumference = 2 times pi times r = 2 times pi times 9 = 18pi
Why others are wrong:
A: 81pi is incorrect because it does not satisfy the equation.
C: 9pi is incorrect because it does not satisfy the equation.
D: 20pi is incorrect because it does not satisfy the equation.