Skip to main content
OlympiadHQ

Browse · MATH

Print

jmc

prealgebra intermediate

Problem

Two concentric circular regions have radii of 1 inch and 10 inches. What is the area, in square inches, outside the smaller region, but inside the larger region? Express your answer in terms of .
Solution
The area of the inner circle is . The area of the outer circle is . Thus, subtracting from , we get .
Final answer
99\pi \text{ square inches}