Geometry

Question Analysis

The main focus is on using the formula for the area of a ring. We need to find the areas of the outer and inner circles and then subtract the area of the inner circle from that of the outer circle.

 

Key Concept Explanation

The area of a circle is calculated using the formula , where  is the radius. For a ring (annulus), the area  is given by , with  being the radius of the outer circle and  being the radius of the inner circle.

 

Step - by - Step Solution

1. Identify the radii: The outer radius  cm and the inner radius  cm.

2. Apply the formula for the area of the ring:

Substitute the values into .

First, calculate  and .

Then

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