Let be the area of a circle with radius . If , find when . Thanks Moderator edit: Deleted post restored. Thread closed.
Last edited by mr fantastic; Nov 19th 2010 at 08:01 PM. Reason: Restored deleted question.
Follow Math Help Forum on Facebook and Google+
$\displaystyle \dfrac{dA}{dt} = \dfrac{dA}{dr} \times \dfrac{dr}{dt}$ You know dr/dt. You know that $\displaystyle A = \pi r^2$ Find dA/dr and plug in r = 1 and plug that in the chain rule equation.
$\displaystyle A=\pi\;r^2$ $\displaystyle \dfrac{dA}{dt} = 2\pi r \; \dfrac{dr}{dt}$
View Tag Cloud