cos(33°-x)sin(63°-x)-cos(x+57°)sin(27°+x)=cos[90°-(x+57°)]sin[90°-(x+27°]-cos(x+57°)sin(x+27°)=sin(x+57°)cos(x+27°)-cos(x+57°)sin(x+27°)=sin[(x+57°)-(x+27°)]=sin30°=1/2