Geometry

Question Analysis

The main focus is using the formula for the area of a ring to find the inner radius first, and then calculating the inner diameter.

 

Key Concept Explanation

The area of a ring is given by the formula , where  is the area of the ring,  is the outer radius, and  is the inner radius. This formula is based on the difference between the area of the outer circle () and the area of the inner circle ().

 

Step - by - Step Solution

1. Start with the ring - area formula: .

Substitute  and  into the formula: .

Divide both sides of the equation by :

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