1+cos120 поделить на sin120
1+cos120/sin120 ; 1+cos(90+30)/sin(90+30) ; 1+(-sin30)/cos30 ; 1-1/2 / √3/2 = 0,5 / √3/2 = 1/√3 = √3/3
= cos120=cos(90+30)=sin30=1/2=0.5