1.58: A circle has radius and area A

A circle has radius $\displaystyle 3r\,\mathrm{cm}$ and area $\displaystyle A\,\mathrm{cm}^2$.

Given that the value of $\displaystyle r$ increases by $\displaystyle 0.05\%$,

use calculus to find an estimate for the percentage increase in the value of $\displaystyle A$.