cho tam giac ABC co AB=AC, tia phan giac cua goc A cat canh BC tai D.Lay E tren AD.CMR

a. Tam giac AEB=tam giac AEC 

b. ED la tia phan giac cua goc BEC 

c. AD vuong goc voi BC

\(cho\Delta ABC\)co AB=3cm, AC=4cm, BC=5cm

a, \(\Delta ABC\)la \(\Delta\)gi

b, ve BD la tia phan giac cua goc B. tren BC lay diem E sao cho AE=AB . CMR: AD=DE

c, CM: \(AE\perp BD\)

d, keo dai BA cat BD tai F . Cm : AE//FC

Cho tam giac ABC co goc B=80 do; goc C=40 do. Tia phan giac cua goc A cat BC o D.

a. Tinh goc BAC, goc ADC

b. Goi E la mot diem tren canh AC sao cho AE=AB. Chung minh: \(\Delta ABD=\Delta AED\)

C. Tia phan giac cua goc B cat AC tai I. Chung minh BI//DE

cho ΔABC vuong tai A va ABC=60

a, so sanh AB va AC

b, Tren BC lay D sao cho BD =AB. Qua D dung cac duong thang vuong goc voi BC cat tia doi AB tai E. CHung minh ΔABC=ΔDEB

c, goi H la giao diem cua ED va AC. chung minh BH la tia phan giac cua ABC

d,Qua B dung cac duong thang vuong goc voi AB cat duong thang ED tai K vhng minh ΔHBK deu

Cho ΔABC co BC lon nhat. Tren Bc lay cacs diem D va E sao cho BD=BA va CE=CA. Phan giac ∠B cat AE tai M, phan giac ∠C cat AD tai N. C/m phan giac ∠BAC ⊥ MN

cho tam giac ABC co AB<AC.tia phan giac cua goc BAC cat canh BC tai D.goi M va N lan luot la hinh chieu cua B va C tren duong thang AD.

a,cm  \(\Delta\)MBD dong dang voi tam giac NCD

b,biet AB =24 cm , AC=28cm .tinh \(\frac{BM}{CN}\)

c,cm AM . DN=AN.DM

cho tam giac ABC vuong tai A, co duong phan giac BD. Ke DE vuong goc voi BC (E ϵ BC) . tren tia doi cua tia AB lay diem F sao cho AF = CE

chung minh a, ΔABD=ΔEBD

b, BD la duong trung trung truc cua doan thang AE

c, AD < DC

d, goc ADF= goc EDC va E,D,F thang hang

cho Δ ABC vuong tai A co B =60 . tren canh BC lay diem D sao cho BA=BD . TIA phan giac cua B cat AC tai I

a, cm ΔBAD deu

b, cm ΔIBC can

c, CM D la trung diem cua BC

d, cho AB= 6cm . tinh BC va AC