S=0.5*AB*BC*sinB
sinB=10sqrt(3)/(5*4)=sqrt(3)/2
B=60 градусов
AC^2=AB^2+BC^2-2*AB*BC*cosB=25+49-2*5*4*0.5=25+49-20=54
AC=sqrt(54)=3sqrt(6)
S=0.5*AB*BC*sinB
sinB=10sqrt(3)/(5*4)=sqrt(3)/2
B=60 градусов
AC^2=AB^2+BC^2-2*AB*BC*cosB=25+49-2*5*4*0.5=25+49-20=54
AC=sqrt(54)=3sqrt(6)