f(x)=sinπ/3+cos(4x-π/6)
=cos(4x-π/6)+√3/2
最小正周期T=2π/4=π/2
单调递减区间[π/24+kπ/2,7π/24+kπ/2](k∈Z)
PS：无论你sin后面是4x还是4π,答案都一样