f(x)=2cosx/2×(√2sin(x/2+π/4)+ tan(x/2+π/4)×tan(x/2-π/4))
=√2[sin(x+π/4)+sin(π/4)] + [1+tan(x/2)]/[1-tan(x/2)]×[tan(x/2)-1]/[1+tan(x/2)]
=√2sin(x+π/4)
最大值=√2
最小正周期=2π
sinx的增区间是:-π/2+2kπ≤x≤π/2+2kπ
带入-π/2+2kπ≤x+π/4≤π/2+2kπ
所以增区间-3π/4+2kπ≤x≤π/4+2kπ
减区间同理
如有不懂请追问或HI我
谢谢采纳!