Geometry

Question Analysis

The main focus is applying the formula for the area of a ring. We need to find the outer radius from the given outer diameter 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, the area , with  being the outer radius and  being the inner radius. This formula subtracts the area of the inner circle from the area of the outer circle.

 

Step - by - Step Solution

1. Determine the outer radius:

Given the outer diameter  mm, the outer radius  mm.

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

Substitute  mm and  mm into .

Calculate

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