Geometry

Question Analysis

The main focus is using the formula for the area of a ring. Given the outer diameter and inner radius,  we need to first find the outer radius and then calculate the difference between the areas of the outer and inner circles.

 

Key Concept Explanation

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

 

Step - by - Step Solution

1. Calculate the outer radius:

Given the outer diameter  m, the outer radius  m.

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

Substitute  m and  m into the formula .

Calculate  and

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