# Math Help - applincations of derivatives

1. ## applincations of derivatives

The diameter of a tree was 10 in. During th following year, the circumference increased 2 in. About how much did the tree's diameter increase?

The teacher gave us some problems before he went into it very much, to see what we can do ourselves...
I am not sure what to do with this one. Can someone help? Thanks

2. Originally Posted by Morgan82
The diameter of a tree was 10 in. During th following year, the circumference increased 2 in. About how much did the tree's diameter increase?

The teacher gave us some problems before he went into it very much, to see what we can do ourselves...
I am not sure what to do with this one. Can someone help? Thanks
$\frac{dC}{dt} = 2$ in/yr

$C = 2\pi r$

$\frac{dC}{dt} = 2\pi \frac{dr}{dt}$

$D = 2r$

$\frac{dD}{dt} = 2 \frac{dr}{dt}$