1) tg 2x <= 1;
3) ctg (x/2) < √3/3;
4) ctg (x/3) >= 1.
[m]-\frac{\pi}{2}+\pi k < 2x \leq \frac{\pi}{4}+\pi k[/m], k ∈ Z
[m]-\frac{\pi}{4}+\frac{\pi}{2} k < x \leq \frac{\pi}{8}+\frac{\pi}{2} k[/m], k ∈ Z
3)
[m]\frac{\pi}{3}+\pi k < \frac{x}{2} < \pi +\pi k[/m], k ∈ Z
[m]\frac{2\pi}{3}+2\pi k <x< 2 \pi +2 \pi k[/m], k ∈ Z
4)
[m]0 +\pi k < \frac{x}{3} < \frac{\pi}{4} +\pi k[/m], k ∈ Z
[m]3\pi k <x < \frac{3 \pi}{4} +3 \pi k[/m], k ∈ Z