What is the derivative of csc(3x)?
I'll add some detail: how you get there.
...you use the rule for finding the derivative of the quotient of 2 functions.
So, you start by rewriting
Here, g(x) = 1, g'(x) = 0, h(x) = sin(3x), h'(x) = 3cos(3x)
Put all this together: