A circular disc of radius `3` `cm` is being heated. Due to expansion, its radius increases at the rate of `0.05` `cm`/`sec`. Find the rate at which its area is increasing when radius is `3.2`` cm`.

Explanation

To solve the problem, we need to find the rate at which the area of the circular disc is increasing when the radius is 3.2 cm. We will use the concept of derivatives to find this rate.

### Step-by-Step Solution:

1. **Understand the Given Information:**
- Radius of the disc, \( r = 3.2 \) cm.
- Rate of change of radius, \( \frac{dr}{dt} = 0.05 \) cm/s.

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