f(x)=x+2cosx f'(x)=1-2sinx=0,得x=π/6 f(π/6)=π/6+2cos(π/6)=π/6+√3 f(0)=2 f(π/2)=π/2 π/6+√3>2>π/2 f(x)=x+2cosx在[0,π/2]上的最大值是π/6+√3、最小值是π/2