Set 5: Circles (Intermediate)

[Variation 2] **Choice A is the best answer.** A = pi times r squared. 81pi = pi times r squared. r squared = 81. r = 9

Explanation

Answer: A

PROBLEM

Intriguingly, a circle has area 81pi. What is its radius?

A circle has area 81pi. What is its radius?

✓ Correct

Detailed Explanation

[Variation 2] Choice A is the best answer. A = pi times r squared. 81pi = pi times r squared. r squared = 81. r = 9

Why others are wrong:

B: 11 is incorrect because it does not satisfy the equation.

C: 18 is incorrect because it does not satisfy the equation.

D: 10 is incorrect because it does not satisfy the equation.

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