sinx-cosx
=√2(√2/2sinx-√2/2cosx)
=√2(cosπ/4sinx-sinπ/4cosx)
=√2sin(x-π/4)>0
正弦值在 0到π上大于零
∴x-π/4∈(2kπ,π+2kπ)
∴x∈(2kπ+π/4,5π/4+2kπ)
又∵,x∈[0,2π] k取零
∴ x∈(π/4,5π/4)
sinx-cosx
=√2(√2/2sinx-√2/2cosx)
=√2(cosπ/4sinx-sinπ/4cosx)
=√2sin(x-π/4)>0
正弦值在 0到π上大于零
∴x-π/4∈(2kπ,π+2kπ)
∴x∈(2kπ+π/4,5π/4+2kπ)
又∵,x∈[0,2π] k取零
∴ x∈(π/4,5π/4)