cho tam giac abc vuong tai BC.tren canh AB lay diem D sao cho AD=AC ke qua D duong thang vuong goc voi Ab cat bc tai E .AE cat CD tai I

a)CM AE la phan giac goc CAB

b)CM AE la trung truc cua CD

c) so sanh CD va BC

d) M la trung diem cua BC,BM cat BI tai G,CG cat DB tai k.CM K la trung diem cua DB

cho tam giac ABC can tai A.tren canh bc lay diem D trên tiadoi cua CB lay diem E sao cho BD = CE tu D va E ke cac duong thang vuong goc voi BC lan luot cat AB o M cat AC o N. I la trung diem cua MN.CMR duong thang vuong goc voi MN tai I luon di qua 1 diem co dinh khi D thay đoi trên canh BC

Cho tam giac ABC vuong tai A co AB=3cm,AC=4cm.Goi AM la duong trung tuyen cua tam giac ABC tren tia doi cua tia AM lay diem D sao cho AM=MD

a)Tinh BC

b)C/m AB // CD

c)C/m goc BAM > goc CAM

d)Goi H la trung diem AM,tren duong thang AH lay E sao cho AH=HE , CE cat AD tai F . C/m F la trung diem CE

Cho tam giac ABC vuong tai A co AB=3cm,AC=4cm.Goi AM la duong trung tuyen cua tam giac ABC tren tia doi cua tia AM lay diem D sao cho AM=MD

a)Tinh BC

b)C/m AB // CD

c)C/m goc BAM > goc CAM

d)Goi H la trung diem AM,tren duong thang AH lay E sao cho AH=HE , CE cat AD tai F . C/m F la trung diem CE

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 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 ( ab>ac ), m la trung diem cua bc. duong thang di qua m vuong goc voi tia phan giac cua goc a tai h cat canh ab, ac lan luot tai e va f. CMR:

1)cho tam giac abc co goc b=goc c.goi i la trung diem cua canh bc.tren canh ab laydiem d,tren tia di lay diem e sao cho i la trung diem de.cm:

a,bd=ce;

b,cb la tia phan giac cua goc ace

cho tam giac ABC co goc A=90 do va AB=AC.Tren canh AB,AC lay tuong ung 2 diem D va E sao choAD=AE.Tu A va D ke duong vuong goc voi BE cat BC tai M va N.Tia ND cat CA o I.CM:

a,A la trung diem cua CI.

b,CM=MN

Ve tam giac ABC va DBC lan luot vuong can tai A va D (A va D nam tren hai nua mat phang khac nhau bo BC)

a)CM: tam giac ABD vuong can

b)Goi E la trung diem cua BC. Tu C ke duong thang vuong goc voi AE, cat AE tai M, cat AB tai F. CMR:F la trung diem cua AB