How do you differentiate f(x)=cot(3x) using the chain rule?

1 Answer
Feb 9, 2016

dudx=3csc2(3x)

Explanation:

First, I assume you know that the derivative of cotx is csc2x.

We substitute u=3x.

Therefore,

dudx=3.

Now we use the chain rule.

ddx(cot(3x))=ddx(cot(u))

=ddu(cot(u))dudx

=csc2(u)3

=3csc2(3x)