Question

[nguyen thanh thao]

tam giac ABC , 3 duong cao AD,BE,CF cat nhau tai H

a)CM:AH.HD=CH.HF
b)CM:tam giac CEH dông dang voi tam giac BEA

c)CM:FD.CH=CD.DH

d)CM:tam giac BDF dong dang voi tam giac BAC

e)CM:FH la tia phan giac cua goc DFE

f)Goi K la giao diem cua DF va BE

CM: HK.BE=BK.HE