f(x)=sin(2x+三分之派)+sin(2x-三分之派)+2cos方x-1
=sin2x*cos(3分之π) + cos2x*sin(3分之π) + sin2x*cos(3分之π) - cos2x*sin(3分之π) +cos2x
=2sin2x*cos(3分之π)+cos2x
=2sin2x* 2分之1+cos2x
=sin2x+cos2x
=根号2*[sin2x*cos(4分之π)+ cos2x*sin(4分之π)]
=根号2*sin(2x + 4分之π)
所以可知函数最小正周期T=2π/2=π