K
koisiujing
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
![](https://blog.hocmai.vn/wp-content/uploads/2017/07/hot.gif)
Cho tam giác ABC đường cao AH .goi D, E la diem doi xung cua H qua AB va AC
a.xac dinh phep quay bien diem D thanh diem E
b.Goi M,N la giao diem cua D,E voi AB,AC .xac dinh phep doi xung truc bien HM thanh HN
c.chung minh 3 duong thang BN,CM,AH dong qui
a.xac dinh phep quay bien diem D thanh diem E
b.Goi M,N la giao diem cua D,E voi AB,AC .xac dinh phep doi xung truc bien HM thanh HN
c.chung minh 3 duong thang BN,CM,AH dong qui