Question

详细微分一下sinx和cosx 用f（x+h）-f（x）/h h无限接近于0

Answer 1

是求导过程,利用的是和差化积公式以及sinx和x是等价无穷小sin'x=lim(sin(x+h)-sinx)/h=2limcos(x+h/2)sin(h/2)/h=2limcos(x+h/2)*(h/2)/h=limcos(x+h/2)=cosxcos'x=lim[cos(x+h)-cosx]/h=-2limsin(x+h/2)sin(h/2)/h=...