Integration - calculus

[Ambar]

A circular disc of radius 3 cm is being heated. Due to expansion, it's radius increases at the rate of 0.05 cm/s . Find the rate at which it's area is increasing when radius is 3.2 CMS

Some one please explain the way this sum is done with the help of calculus

[Lord Antares]

This sounds like homework. We're not supposed to just give answers for homework, we're supposed to help you through it. So, if this is homework, what are your thoughts on it? Do you see a link between the numbers?

[Ambar]

Yea, it's hw I did not understand the way these sums are done though I have understood the concept of derivatives and differentiation but dese sums r totally new and different for me 2 so I wanted someone to guide me through it , yea I don't just want the answer I want the explanation or guidance so that I can answer rest of the questions myself

Edited July 11, 2017 by Ambar

[Country Boy]

Calculus, yes, but not integration. Since [math]A= \pi r^2[/math], [math]dA= 2\pi r dr[/math]. You are told that r= 3.2 and that dr= 0.05.

Edited July 11, 2017 by Country Boy

[Ambar]

Thank so much