1）f(x)=[1+cos(π/2+2x)]/2+[1-cos2x]/2+1=2-[sin2x+cos2x]/2=2-sin(2x+π/4)/√2
最小正周期T=2π/2=π
最大值为2+1/√2
最小值为2-1/√2
2) f(x)>=2即
2-sin(2x+π/4)/√2>=2
即sin(2x+π/4)