# Math 31 Rates of change

1. Apr 13, 2005

### Peppy

I need help with the question: The height h of an equilateral triangle is increasing at a rate of 3cm/min. How fast is the area changing when h is 5 cm.

2. Apr 13, 2005

### dextercioby

What's the area?What's the height?Can u write the former as a function of the latter?

Daniel.

3. Apr 14, 2005

### James R

You want $dA/dt$. Use the chain rule:

$$\frac{dA}{dt} = \frac{dA}{dh} \frac{dh}{dt}$$

Of course, you'll need to work out what the two derivatives on the right are.