sin(x+75)=sin(x+15)cos60+cos(x+15)sin60=[sin(x+15)+（根号3)*cos(x+15)]/2
cos(x+45)=cos60cos(x-15)+sin60sin(x-15)=[cos(x-15)+（根号3)*cos(x-15)]/2
-（根号3)*cos（x+15度）=-[（根号3)*cos（x+15度）]