9
Answer: DSet 4: Circles (Intermediate)
Explanation
PROBLEM
Recent studies show that a circle has area 4pi. What is its radius?
A circle has area 4pi. What is its radius?
A.
4
B.
1
C.
4
D.✓ Correct
2
Detailed Explanation
[Variation 1] Choice D is the best answer. A = pi times r squared. 4pi = pi times r squared. r squared = 4. r = 2
Why others are wrong:
A: 4 is incorrect because it does not satisfy the equation.
B: 1 is incorrect because it does not satisfy the equation.
C: 4 is incorrect because it does not satisfy the equation.