题目内容
如图△ABC中,E、F为BC的三等份点,M为AC的中点,BM与AE、AF分别交于G、H,则BG:GH:HM=______.

过点M作MK∥BC,交AF,AE分别于K,N,
∵M是AC的中点,
∴
=
=
=
=
,
∵E、F是BC的三等分点,
∴BE=EF=FC,
∴MN=2NK,
∵
=
=
,
=
=1,
∴MH=
BH,MG=BG,
设MH=a,BH=4a,BG=GM=
,
∴GH=GM-MN=
,
∴BG:GH:HM=
:
:a=5:3:2.
故答案为:5:3:2.

∵M是AC的中点,
∴
| MN |
| EC |
| NK |
| EF |
| AN |
| AE |
| AM |
| AC |
| 1 |
| 2 |
∵E、F是BC的三等分点,
∴BE=EF=FC,
∴MN=2NK,
∵
| MH |
| BH |
| MK |
| BF |
| 1 |
| 4 |
| MG |
| BG |
| MN |
| BE |
∴MH=
| 1 |
| 4 |
设MH=a,BH=4a,BG=GM=
| 5a |
| 2 |
∴GH=GM-MN=
| 3a |
| 2 |
∴BG:GH:HM=
| 5a |
| 2 |
| 3a |
| 2 |
故答案为:5:3:2.
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