f(x)=a·b=sinx/3cosx/3+cosx/3√3cosx/3
=1/2sin2x/3+√3/2(1+cos2x/3)
=√3/2+sin2x/3cosπ/3+cos2x/3sinπ/3
=√3/2+sin(2x/3+π/3)
(1) 递增区间
2kπ
f(x)=a·b=sinx/3cosx/3+cosx/3√3cosx/3
=1/2sin2x/3+√3/2(1+cos2x/3)
=√3/2+sin2x/3cosπ/3+cos2x/3sinπ/3
=√3/2+sin(2x/3+π/3)
(1) 递增区间
2kπ