Geometry

Question Analysis

The core of this problem is applying the formula for the area of a ring. Given the outer and inner radii, we must use the appropriate formula to find the area between the two circles.

 

Key Concept Explanation

The area of a circle is calculated by , where  is the radius. For a ring (annulus), the area formula is , with  being the outer radius and  the inner radius. This formula is based on subtracting the area of the inner circle from that of the outer circle.

 

Step - by - Step Solution

1. Identify the values of  and : Here,  m and  m.

2. Substitute into the ring - area formula:

First, calculate  and .  and