例8设y=sinx,求ym) 解卩=c0sx=sin(x+ 2 y cos(x+=sin(x 2,)=sin(x+2.2 y"=c0s(x+2·)=sin(x+3.“ T =sin(x+n. 2 同理可得()(m)=c0x+B.个 2例8 sin , . (n) 设 y = x 求y 解 y = cos x ) 2 sin(  = x + ) 2 cos(  y = x + ) 2 2 sin(  +  = x + ) 2 sin( 2  = x +  ) 2 cos( 2  y = x +  ) 2 sin( 3  = x +   ) 2 sin( ( )  y = x + n n ) 2 (cos ) cos( ( )  x = x + n n 同理可得