Find the rate of change of the area of a circle with respect to its radius r when(a) `r = 3 c m` (b) `r = 4 c m`

Explanation

To find the rate of change of the area of a circle with respect to its radius \( r \), we start with the formula for the area of a circle:

\[ A = \pi r^2 \]

### Step 1: Differentiate the Area with Respect to the Radius

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