Multiple choice

The circumference of a circle is $30\pi$. What is its area?

  1.  $15\pi$
  2.  $225\pi$
  3.  $400\pi$
  4.  $900\pi$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Circumference C = 2 * pi * r = 30 * pi, so r = 15. The area A = pi * r^2 = pi * 15^2 = 225 * pi.

AI explanation

Using the circumference formula, 2 times pi times radius equals 30 pi, which means the radius is 15. Apply the area of a circle formula, pi times radius squared, to get pi times 15 squared. This calculates to 225 pi.

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