sin(50+x)cos(10-x)-cos(130-x)sin(170+x)
=sin(50+x)cos(10-x)+cos(50+x)sin(10-x)
=sin(50+x+10-x)
=sin60
=√3/2我解出来是sin(50+x)cos(10-x)+cos(50-x)sin(10+x)那不对呀sin(170+x)=sin[180-(170+x)]=sin(10-x)