f(x)=sinx-cosx=√2(√2/2sinx-√2/2cosx)=√2(sinxcosπ/4-cosxsinπ/4)=√2sin(x-π/4)(1)因为-1≤sin(x-π/4)≤1,所以-√2≤f(x)≤√2,即f(x)的值域是[-√2,√2].(2)当π/2+2kπ≤x-π/4≤3π/2+2kπ,即3π/4+2k...