If the area of circle increases at a uniform rate, then prove that the perimeter varies inversely as the radius.

Explanation

We have,


`A=pi r^{2}` and Let `frac{d A}{d t}=k`



`{P}=2 pi {r}`




`frac{{d} A}{{dt}}=2 pi {r} frac{{dr}}{{dt}}`



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