Question

1.cho tam giac ABC co truc tam H,  va N la trung diem BC va AC ; o la giao diem trung truc cua tam giac ABC. CMR:

a, tam giac OMN dong dang tam giac HAB. tim ti so dong dang

b, so sanh AH va OM

c, goi G la trong tam cua tam giac ABC. CM tam giac HAG dong dang tam giac OMG

d, H,G,O thang hang va HG=2GO

2. 1 duong thang di qua A cua hinh binh hanh ABCD cat BD,BC,CD lan luot tai E,K,G. CMR:

a, AE² = KE . EG

b, \(\frac{1}{AE}\)=\(\frac{1}{AK}\)+\(\frac{1}{AG}\)

c, BK .DG khong doi khi duong thang thay doi quanh A