周期T=2π/ω+2kπ,ω=-1,所以周期T=2kπ-2π,（k为整数）单调区间,由2kπ-π/2≤π/4-x≤2kπ+π/2,得3π/4-2kπ≤x≤-2kπ-π/4,k为整数单调递增区间 [3π/4-2kπ,≤-2kπ-π/4]由2kπ+π/2≤π/4-x≤2kπ+3π/2,...