EF为AB,AC中点
EF//BC,且EF=BC/2
过A作AD⊥BC交BC于D,过F作FG⊥BC交BC于G,过CH⊥EF,交EF延长线于H
CH=FG
FG/AD=CF/AC=1/2
S△ABC=AD*BC/2
S△CEF=EF*CH/2=[(BC/2)*(AD/2)]/2=S△ABC/4=6
EF为AB,AC中点
EF//BC,且EF=BC/2
过A作AD⊥BC交BC于D,过F作FG⊥BC交BC于G,过CH⊥EF,交EF延长线于H
CH=FG
FG/AD=CF/AC=1/2
S△ABC=AD*BC/2
S△CEF=EF*CH/2=[(BC/2)*(AD/2)]/2=S△ABC/4=6