# Thread: Differentiate a function using composite rule

1. ## Differentiate a function using composite rule

How can I do this differentiation to this function ?

$
f(x) = e^{cos(x)+sin(x)}
$

Thank you very much!

2. Use the chain rule with $u=\cos x +\sin x$ and $f(u(x))=e^{u(x)}$

$\frac{df}{dx}=\frac{df}{du}\frac{du}{dx}$

3. If you're doing the OU course MST121 the answer is explained in book C2. I will find the page when at home.