例2设函数f(x)=sinx,求(sinx)及(sinx) 解(sinx)'=lim sin(x+h-sin x h→>0 h= SI = lim cos(x+。) coS h→>0 2 即sinx)=cosx ∴(SInx I cos x 2 上页例 2 ( ) sin , (sin ) (sin ) . 4 = =   x 设函数 f x x 求 x 及 x 解 h x h x x h sin( ) sin (sin ) lim0 + −  = → 2 2 sin ) 2 lim cos( 0 h h h x h = +  → = cos x . 即 (sin x) = cos x. 4 4 (sin ) cos  =  =   = x x x x . 22 =