CHo tam giac ABC can tai A , goc A = 20 do. Ve tam giac DBC ( D nam trong tam giac ABC). tia phan giác goc ABD cat AC tai M. CHung minh : a, tia AM la tia phan giac goc BAC
b, AM= BC
Cho tam giac ABC vuong tai A co AB=3cm;AC=6cm
a,tinh BC
b,Goi E la trung diem cua AC,phan giac cua goc A cat BC tai D.Chung minh tam giac ABD=tam giac AED
c,ED cat AB tai M.Chung minh tam giac BAC= tam giac EAM.Suy ra tam giac MAC vuong can
Cho tam giac abc tia phan giac cua goc abc cat canh ac tai d tu d ke duong thang //bc dg thanh nay cat canh ab tai diem e tia phan giac cua goc aed cat ad tai f ctr a,tam giac ebdco 2 goc bang nhau b,ef//bd
CHO TAM GIAC ABC VUONG TAI A CO AB=9 AC=A2
a; TINH BC
b; TIA PHAN GIAC GOC B CAT AD TAI D KE DM VUONG GOC BC TAI M CM TAM GIAC ABD=MBD
c; GOI GIAO DIEM CUA DM VA AB LA E CM TAM GIAC BEC CAN
cho tam giac ABC co B=110 do C =50 do phan giac goc ngoai tai dinh A cat tia doi cua tia BC tai D tinh cac goc cua tam giac ABD
CHO tam giac ABC co goc A = 60 do .Cac tia phan giac cua B va C cat nhau tai O va cat AC ,AB lan luot tai D va E .Tia phan giac cua goc BOC cat tai BC tai F .CMR : a. OE=OD=OF . b. Tam giac DEF đêu
cho tam giac abc, ac>ab. Tia phan giac goc a cat bc tai d. Kẻ ah vuong goc bc, m la trung diem cua bc. Chung minh ad nam giua ah va am
Cho tam giac ABC can tai B co goc nhon. Ve tia phan giac cua goc ABC cat tia AC tai K a. Chung minh: tam giac BAK = tam giac BCK
b. Ve trung tuyen AM cua tam giac ABC cat BK tai G. Chung minh: G la trong tam cua tam giac ABC
c. Voi AB = 30cm;AK =18cm. Tinh BG
cho tam giac ABC, biet A= 100*, tia phan giac cua goc B cat AC tai D. CMR BC=BD + AD