f(x)＝1/2sinx+√3/2cosx
＝sinxcos(π/3)+cosxsin(π/3)
＝sin(x+π/3).
∵-1≤sin(x+π/3)≤1,
∴-1≤f(x)≤1.
即f(x)|min＝-1,f(x)|max＝1.为什么到sin（x+π/3）之后就直接是-1那步了？