а) -√3-2sin3x<0

б) ctg ([tex] \frac{ \pi }{2} [/tex]+x)>√3

sin3x>-√3/2-π/3+2πn<3x<4π/3+2πn-π/9+2πn/3<x<4π/9+2πn/3x∈(-π/9+2πn/3;4π/9+2πn/3)πn<π/2+x<π/6+πn-π/2+πn<x<-π/2+π/6+πn-π/2+πn<x<-π/3+πnx∈(-π/2+πn;-π/3+πn)