Practice!

Sample Problem

There are two circles such that the radius of the larger circle is three times the radius of the smaller circle.

(a)   The circumference of the larger circle is times the circumference of the smaller circle.

(b)  What is the ratio of the area of the larger circle to the area of the smaller circle?

Solution

(a)   Because the circumference is 2π times of the radius of the circle, the circumference of the larger circle is 3 times the circumference of the smaller circle.

(b)  The ratio of the area of the larger circle to the area of the smaller circle is 32 = 9.