alleryA circle has circumference $30\pi$ cm. What is its area?
A$150\pi$ sq cm
B$225\pi$ sq cm
C$450\pi$ sq cm
D$900\pi$ sq cm
Answer & Solution
Correct answer: B. $225\pi$ sq cm
From $C=2\pi r=30\pi$, the radius is $r=15$ cm.
Therefore, area $A=\pi r^2=\pi(15)^2=225\pi$ sq cm.
**Option A would result from multiplying by $r$ instead of squaring it.**
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