做辅助点 E1,F1为A1B1,A1C1中点
则 AEF—A1E1F1 :EFBC-E1F1B1C1 =1:3
EF-E1F1B1C1 :EFBC-B1C1 = 1:1
因此 AEF—A1B1C1 :EFBC-B1C1 = 1+1.5:1.5 = 5 :3
做辅助点 E1,F1为A1B1,A1C1中点
则 AEF—A1E1F1 :EFBC-E1F1B1C1 =1:3
EF-E1F1B1C1 :EFBC-B1C1 = 1:1
因此 AEF—A1B1C1 :EFBC-B1C1 = 1+1.5:1.5 = 5 :3