If f(x)=ecos(x)f(x) = e^{\\cos(x)}f(x)=ecos(x), find f′(x)f'(x)f′(x).
ecos(x)e^{\\cos(x)}ecos(x)
cos(x)esin(x)\\cos(x)e^{\\sin(x)}cos(x)esin(x)
−sin(x)ecos(x)-\\sin(x)e^{\\cos(x)}−sin(x)ecos(x)
sin(x)ecos(x)\\sin(x)e^{\\cos(x)}sin(x)ecos(x)