AC^=AB^+BC^-2ABACcosABC=16+36-2*4*6/2=52-24=28
AC=SQRT(28)
AC*BD=AB*BC*sin60
BD=4*6*SQRT(3)/2SQRT(28)=6SQRT(21)/7
AC^=AB^+BC^-2ABACcosABC=16+36-2*4*6/2=52-24=28
AC=SQRT(28)
AC*BD=AB*BC*sin60
BD=4*6*SQRT(3)/2SQRT(28)=6SQRT(21)/7