# Derivative of sin(3x)

1. Jun 5, 2005

### mattmns

Is the derivative of sin(3x) just 3sin(3x) because of the chain rule? IE, let u=3x, then 3sin(u) => 3sin(3x)

Thanks.

Ok, I am pretty sure that is true. How about, $$\lim_{t\rightarrow 0} tln(t)$$

What is the common approach for this problem?

Last edited: Jun 5, 2005
2. Jun 5, 2005

### OlderDan

It's not true because the derivative of sine is not itself

For the limit, you might look for a minimum of the function. Does it have one? More than one? That should get you started.

3. Jun 5, 2005

### p53ud0 dr34m5

i agree with OlderDan.
$$h(x)=f(g(x))$$
if you have that, then:
$$h'(x)=f'(g(x))*g'(x)$$
so, sine is not the derivative of itself.

4. Jun 5, 2005

### mrjeffy321

I think the derivative of sine is cosine,
so the derivative of sin(3x) would be 3cos(3x)

5. Jun 5, 2005

### mattmns

Bah, that is what I meant, sorry. Thanks, been a while since I did a derivative or a limit