2+2cosX≥0.COSX≥－√2/2.
－3π/4+2kπ≤x≤4π/3+2kπ.k∈Z
sinX≥√3/2
.π/3+2kπ≤x≤4π/3+2kπ.k∈Z
tanx>=根号3
x>=kπ+π/3
则x∈[Kπ+π/3,Kπ+π/2)
不懂的欢迎追问,