Cho tam giac ABC co goc ABC= 30do va BAC=130do. Goi Ax la tia doi cua tia AB, duong phan giac cua goc ABC cat phan giac cua goc CAx tai D. Duong thang BA cat duong thang CD tai E. So sanh do dai 2 canh AC va CE
cho tam giac ABC (AB<AC)goi Ax la tia phan giac cua goc A,I la trung diem cua BC. Qua I ke duong thang vuong goc voi Ax cat duong thang AB tai D va duong thang AC tai E
cho tam giac ABC can tai A co A < 90 do, duong vuong goc voi AB tai B va duong thang vuong goc voi AC tai C va chung cat nhau tai M.
a, c/m tgABM = tgACM, AM la phan giac cua goc BAC
b, Qua M ve duong thang song song voi AC, duong thang nay cat AB o D. Tren tia doi cua tia CA lay diem E sao cho CE = DB, c/m tgDBM = tgECM
c, BC cat DM tai F. c/m DF = CE
cho tam giac ABC B=60 tren tia doi BC lay diem E sao cho BE=BA . qua B ve 1 duong thang song song AE cat AC o F a] chung minh BE la phan giac cua goc ABC b] Qua A ve mot duong thang vuong goc BF cat BC tai D .Chung minh tam giac ABC deu c] goi Ax la tia doi cua AB . Chung minh goc CAx =goc CDF d] chung minh AF=FC
Cho tam giac ABC co goc A khac goc B cac tia phan giac trong va ngoai cua goc C lan luot cat duong thang BA tai D va E tinh goc CED theo goc A va goc B cua tam giac ABC
cho tam giac ABC co AB<AC. Goi Ax la tia phan giac cua goc A.Qua trung diem M cua BCke duong thang vuong goc voi Ax cat ca uong thang AB va AC theo thu tu o D va K.Chung minh BD=CE
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 CO AD LA PHAN GIAC CUA GOC A (D THUOC BC). KE DEVUONG GOC VOI AB, KE DF VUONG GOC VOI AC
a, CHUNG MINH TAM GIAC AED= TAM GIAC AFD
b, TIA FD CAT TIA AB TAI P, TIA ED CAT TIA AC TAI Q. CHUNG MINH AP=AQ
c, TIA AD CAT PQ TAI M. CHUNG MINH AM LA DUONG TRUNG TRUC CUA DOAN THANG PQ
d, CHO GOC BAC=50 DO. TINH SO DO GOC APQ VA GOC AQP
Cho tam giac ABC co AB=9cm, AC=12cm, BC=15cm
a) Chung minh ABC la tam giac vuong
b) Tren canh BC lay diem D sao cho CD=CA, qua D ve duong thang vuong goc voi BC cat AB tai E va cat duong thang AC tai F. Chung minh AB=DF.
c) Chung minh tia CE la tia phan giac goc ACB.
d) So sanh AE va BE