6) П/6+2Пk<=3x/4<=3п/2+П/6+2Пk<br> П/9+8Пk/3<=x<=20П/9+8Пk/3<br>7) 2п/3+2Пk<3П/2-x<7П/3+2Пk<br> -5П/6+2Пk8) sin(x+П/3)<=1/2<br> 5П/6+2Пk<=x+П/3<=7П/6+2Пk<br> П/2+2Пk<=x<=5П/6+2Пk<br>