Question

Abby

三角形

如右圖,E是AC中點,2BD=CD,則求
B.
F
(1) AF:FD=?(2分)
(2) ABDF面積與AAEF面積的比為多少?(3分)
A
D ②
E TI (A)
8:1(1)
8:10)

請可以幫一下忙嗎？

Answer 1

Mer

做 EG//AD 交BC於G
則CG:GD = CE:EA = 1:1
故 CG:GD:BD = 1:1:1

因為FD//EG
FD:EG = BD:BG = 1:2
EG//AD => EG:AD = 2:4
AF:FD = 3:1

Mer

因為AF:FD = 3:1
可設 △AFB = 3x，△BDF = x
BF:FE = BD:DG = 1:1
故△AEF = △AFB = 3x
△BDF : △AEF = 1:3