Let f(x)=x-2sinx and derive: f' (x) =1+2cosx > 0: cosx > - 1/2π/2 & lt； X & lt2π/3 Therefore, the function f(x) is a increasing function at (π/2,2π/3), a decreasing function at (2π/3,π), and f(2π/3)=2π/3-√3 in the interval (π/2,π). ...