cos(8x+6)的导数
cos(8x+6)=cos(8x)cos6-sin(8x)sin6
{cos(8x)cos6}'=-8sin(8x)cos6-cos(8x)sin6
{-sin(8x)sin6}'=-8cos(8x)sin6-sin(8x)cos6
原式’=-8sin(8x)cos6-cos(8x)sin6-8cos(8x)sin6-sin(8x)cos6