f(x)=cos2x+√3sin2x
=2sin(2x+π/6)
最小正周期为 2π/2=π
最大值为2
单调增区间
2x+π/6∈[2kπ-π/2,2kπ+π/2]
x∈[kπ-π/3,kπ+π/6]
所以
单调增区间为
[kπ-π/3,kπ+π/6] k∈Z