「例]求函数f(x)=tanx的导数 SIn 解!( (tan x)'=( cos (sin x).cos x-sin x(cos x) 2 cos x cos x coS x-sin x(sin x) cos x 〔tanx)y=secx = 2-secx。 cos x 2021/2/20 cos x2021/2/20 7 ) cos sin (tan ) = (  x x x x x x x x 2 cos (sin ) cos − sin (cos ) = sec . cos 1 cos cos cos sin ( sin ) 2 2 2 x x x x x x x = =  −  − = [例8] 求函数 f (x) = tan x的导数 [解] x x x 2 2 cos 1 (tan ) sec =  =