设x-10°=Ay=3sinA+5sin(A+60°) =3sinA+5sinAcos60°+5cosAsin60° =(11/2)sinA+(5√3/2)cosA =√[(11/2)²+(5√3/2)²]sin(A+∅) =√49sin(A+∅) =7sin(A+∅)正弦的最大值为1,所以,y的最大值为7