y=1/2cosπxcosπ/3-1/2sinπxsinπ/3-sinπxcos5π/6-cosπxsin5π/6
=1/4cosπx-√3/4sinπx+√3/2sinπx-1/2cosπx
=-1/4cosπx+√3/4sinπx
=1/2(sinπxcosπ/6-cosπxsinπ/6)
=1/2sin(πx-π/6)
sin增区间是(2kπ-π/2,2kπ+π/2)
所以即2kπ-π/2
y=1/2cosπxcosπ/3-1/2sinπxsinπ/3-sinπxcos5π/6-cosπxsin5π/6
=1/4cosπx-√3/4sinπx+√3/2sinπx-1/2cosπx
=-1/4cosπx+√3/4sinπx
=1/2(sinπxcosπ/6-cosπxsinπ/6)
=1/2sin(πx-π/6)
sin增区间是(2kπ-π/2,2kπ+π/2)
所以即2kπ-π/2