f(x)=sinx+cosx=√2[sinx*(√2/2)+cosx*(√2/2)]=√2[sinx*cos(π/4)+cosxsin(π/4)]=√2sin(x+π/4)(1)T=2π(2)减区间2kπ+π/2≤x+π/4≤2kπ+3π/22kπ+π/4≤x≤2kπ+5π/4减区间 【2kπ+π/4,2kπ+5π/4】,k∈ ...