M
mr.wai_la
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Cho tam giac ABC nhon AB<AC noi thiep duong tron (O;R) cac duong cao AD BE CF cat nhau tai H chung minh:
EH.BD=ED.HF (cau nay minh giai duoc roi)
a, OA vuong goc voi EF
b, Duong thang EF cat duong tron tai M N ;F nam giua M va E cm AM la tiep tuyen cua duong tron ngoai tiep tam giac MDH
c, Gia su EF=R tinh so do goc BAC
chuc cac ban thanh cong voi bai nay
EH.BD=ED.HF (cau nay minh giai duoc roi)
a, OA vuong goc voi EF
b, Duong thang EF cat duong tron tai M N ;F nam giua M va E cm AM la tiep tuyen cua duong tron ngoai tiep tam giac MDH
c, Gia su EF=R tinh so do goc BAC
chuc cac ban thanh cong voi bai nay
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