f'(x)=wcos(wx-π/6)
因为在(0,4π/3)单调递增,在(4π/3,2π)单调递减
所以f'(4π/3)=0
wcos(4wπ/3-π/6)=0
4wπ/3-π/6=(2k+1)π/2
4wπ/3=(2k+1)π/2+π/6
所以w=(3k+2)/4 k为整数
f'(x)=wcos(wx-π/6)
因为在(0,4π/3)单调递增,在(4π/3,2π)单调递减
所以f'(4π/3)=0
wcos(4wπ/3-π/6)=0
4wπ/3-π/6=(2k+1)π/2
4wπ/3=(2k+1)π/2+π/6
所以w=(3k+2)/4 k为整数