Find the area of a ring whose outer and inner radii are respectively 20 cm and 15 cm

Explanation

To find the area of a ring whose outer radius (R) is 20 cm and inner radius (r) is 15 cm, we can follow these steps:

### Step 1: Identify the radii
- Outer radius \( R = 20 \, \text{cm} \)
- Inner radius \( r = 15 \, \text{cm} \)

### Step 2: Use the formula for the area of a ring
The area \( A \) of a ring can be calculated using the formula:
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