Here it is :
$ \frac{\mathrm d}{\mathrm dx}\left( \int_{\cos x}^{\sin x}{\sin \left( t^3 \right)\mathrm dt} \right) $
I've got the answer but I don't know how to start , what to do ?
Here is the answer : $ \sin \left( \sin^3 x \right)\cos x + \sin \left( \cos ^{3}x \right)\sin x $
So first I calculate the primitive and then I derivate it. But I don't know how to integrate. Should I use 'substitution' method ? I tried but then i was blocked...