Các câu hỏi tương tự
Cho tam giac ABC co AB>AC.M la trung diem cua BC,ke duong thang vuong goc vs tia phan giac cua goc A tu M.Cat nhau tai H va cat AB tai E,AC tai F.CMR
a)BE=CF
b)AE=(AB+AC)/2
BE=(AB-AC)/2
c)goc BME=(goc ACB- goc B)/2
tam giac ABC co ab>ac tu trung diem M cua BC ve mot duong thang vuong goc voitia phan giac cua gocA cat tia phan giac tai H cat AB,AC lan luot tai E va F chung minh
a) BE=CF
b) ae=ab+ac/2
be=ac-ac/2
c) goc bme=acb-b/2
Cho tam giac ( AB>AC) ,M la trung diem BC. Duong thang di qua M va vuong goc voi tia phan giac cua goc A tai H cat hai tia AB, AC lan luot tai E va F.Chung minh rang :
a) EF^2/4+AH^2=AE^2
b) 2gocBME=gocACB-goc B
c) BE=CF
cho tam giac abc , ab > ac tu trung diem m cua bc ve 1 duong thang vuong goc voi phan giac cua goc a tai h cat ab ac lan luot la e va f
cm be=cf
1/Cho tam giac ABC co goc A=120 do.Cac tia phan giac BE, CF cua ABC va ACB cat nhau tai I (E,F lan luot thuoc cac canh AC,AB).Tren canh BC lay 2 diem M,N sao cho BIM=CIN=30 do.
a)Tinh so do cua goc MIN
b)Chung minh CE+BF<BC
2/Cho tam giac DEF vuong tai D va DF>DE, ke DH vuong goc voi EF (H thuoc EF). Goi M la trung diem cua EF.
a)Chung minh goc MDH=goc E-goc F
b)Chung minh EF-DE>DF-DH
Cho tam giac ABC co AB = AC va goc A nhon. Goi M la trung diem cua BC.
a) CM tam giacAMB = tam giacAMC
b) cm AM la tia phan giac cua goc BAC
c) AM la duong trung truc cua BC
d) Cac duong thang qua B, C lan luot vuong goc voi AB, AC cat nhau tai H. CM rang: 3 diem A , M ,H thang hang
1 CHO TAM GIAC VUONG CAN ABC ( AB=AC ) .TIA PHAN GIAC CAC GOC B VA C CAT AC VA AB LAN LUOT TAI E VA D
a) CMR : BE=CD VA AD=AE
b) GOI I LA GIAO DIEM CUA BE VA CD . AI CAT BC O M .CMR CAC TAM GIAC AMB ,AMC LA TAM GIAC CAN
c) TU A VA D VE CAC DUONG THANG VUONG GOC VOI BE ,CAC DUONG NAY CAT BC LAN LUOT TAI K VA H . CMR KH=KC
cho tam giac abc co goc c+90 do=goca ve ah vuong goc bc duong thang vuong goc voi ab tai a cat bc tai d goi m la giao diem cua cac tia phan giac goc bah va adh chung minh goc bah=2c chung minh mavuong goc ac
Cho tam giac ABC can tai A co AD la duong trung tuyen
a)Chung minh tam giac ABD= tam gaic ACD va AD vuong goc voi BC
b)Cho AB=10cm,BC=16cm. Tinh do dai AD va so sanh cac goc cua tam giac ABC.
c) Ve duong trung tuyen CF cua tam giac ABC cat AD tai M. Tinh do dai AM.
d) Ve DH vuong goc AC tai H, tren canh AC va canh DC lan luot lay hai diem E,K sao cho AE=AD va DK=DH. Chung minh: EK vuong goc voi BC