1. sin5x=-K(3)/2; 5x=((-1)(k+1))*p/3+pn, х= ((-1)(k+1))*p/15+(pn)/5,nєZ.
2. К(3)*tg(a)-1= К(3)*tg(a)-tg(a)ctg(a)=tg(a)*(K(3)-ctg(a)) или так:
К(3)*tg(a)-1= К(3)*(sin(a)/cos(a))-1= (К(3)*sin(a)-cos(a))/cos(a)=2*((К(3)/2)*sin(a)-(1/2)*cos(a))/cos(a)=2*(cos(p/6)sin(a)-sin(p/6)cos(a))/cos(a)=2*sin(a-p/6)*(1/cos(a))