设t=2x+10,则y=3sint + 5sin(t+60) =3sint + 5sint*cos60 + 5cost*sin60 =5.5sint + (5√3/2)cost =√(5.5^2+25*3/4)sin(t+α)其中tanα=5.5/(5√3/2);因为x∈R,所以t+α∈R,所以sin(t+α)最大值为1所以y的最大值为y...