# Thread: Last differential question. Trig inside a trig.

1. ## Last differential question. Trig inside a trig.

f(x) = 9sin(cos(x^6))

I think im supposed to use the chain rule here but not sure how.

2. $f(x)=9\sin(\cos x^6)\implies f'(x)=9\cos(\cos x^6)\cdot(\cos x^6)'$

Can you take it from there?

3. yes yes. thank you very much. i really need to study this mess.