(1)AD⊥AE,DC⊥CF==>A'D⊥A'E, A'D⊥A'F==>A'D⊥平面A'EF==>A'D⊥EF(2)BE=BF=BC/4=1/2 高h=AD=2S△BEF=(1/2)*(1/2)*(1/2)=1/8=S△A'EF三棱锥VD-A'EF=(1/3)*S△A'EF*h=(1/3)*(1/8)*2=1/12
