Two circles have the same center C. (Circles which have the same center are called concentric.) The larger circle has radius 10 and the smaller circle has radius 8. Determine the area of the ring between these two circles.
The area of large circle is 100pi (pi*10^2)
The area of short circle is 64pi (pi*8^2)
100pi-64pi = 36pi
For this question, you don't have to have any formula for finding the area of the ring, all you need to do is subtract the area of the smaller ring from the bigger one.
So, let us figure out the areas of each of the circles.
C1 = pi*r^2 = pi * 8^2 = 64pi
C2 = pi*r^2 = pi * 10^2 = 100pi
Now that we have the two areas, we can subtract C1 from C2 to get our final answer.
C2 - C1 = 100pi - 64pi = 36pi
So, the area of the ring between these two circles is 36pi.