When the radius of a circle is tripled, how are the area and circumference of the circle affected?

(A) The area is 9 times as large and the circumference is 3 times as large.

(B) The area is 3 times as large and the circumference is 9 times as large.

(C) The area is 3 times as large and the circumference is 6 times as large.

(D) The area is 6 times as large and the circumference is 3 times as large.

(E) The area is 3 times as large and the circumference is 3 times as large.
Suppose that the initial radius of the circle is 1 . Then its initial area is $\pi(1)^{2}=\pi$ and its initial circumference is $2 \pi(1)=2 \pi$.

When the radius is tripled, the new radius is 3 .

The new area is $\pi(3)^{2}=9 \pi$ and the new circumference is $2 \pi(3)=6 \pi$ so the area is 9 times as large and the circumference is 3 times as large.

ANSWER: (A)