例4设y=sinx,求y) 解y=c0sx=sin(x+) y=cos(x+ =sin(x++=sin(x+2. 7 C 22 2 J=C0s(x+2.2 )=sin(x+3·) 。· y(n)=sin(x+n T 同理可得(c0sx))=co(x+n5)例4 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