f(x)=sin(2x+派/4)+cos(2x+派/4) =sin2xcos(π/4)+cos2xsin(π/4)+cos2xcos(π/4)-sin2xsin(π/4) =√2cos(2x)(1)2x=kπ对称轴:x=kπ/2(2)增区间 2kπ-π≤2x≤2kπkπ-π/2≤x≤kπ增区间[kπ-π/2,kπ],k∈Z减区间 2kπ≤2x≤2kπ+πkπ≤x≤kπ+π/2增区间[kπ,kπ+π/2],k∈Z