cho hinh thoi ABCD co AC = AB. Moi duong thang bat ki qua B cat tia doi tia AD tai E, cat tia doi tia CD tai F, AF cat CE tai O.
CM a) AF :CE khong doi
b) tam giac AEB dong dang voi tam giac CED
ko can ve hinh lam nhanh minh tick
Những câu hỏi liên quan
Cho hinh vuong ABCD. Goi E la mot diem tren canh BC. Qua B ke tia Bx vuong goc voi AE, Ax cat CD tai F. Trung tuyen AI cua tam giac AEF cat CD tai K. Duong thang qua E song song voi AB va cat AI tai G. CM:
a) AE = AF va tu giac EGFK la hinh thoi
b) AF2 = FK.FC
c) Khi E thay doi tren BC thi chu vi tam giac EKC van khong doi
cho hinh thoi ABCD , góc A = 60 do
1 duong thang bat ki di qua C cat tia doi cua tia BA, DA tai M , N
BN cat DM tai K
a, chung minh tam giac MBD dong dang voi tam giac BDN
b, tinh goc BKD
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
a)Xét ΔABM vuông và ΔACM vuông có:
AM chung
AB=AC
=> ΔABM = ΔACM
=> BAM = CAM ( 2 góc t.ư)
=> AM là p/g của góc BAC
Qua dinh A cua hinh vuong ABCD ta ke 2 duong thang Ax,Ay vuong goc voi nhau. Ax cat canh BC tai diem P va cat tia doi cua tia CD tai diem Q. At cat tia doi cua tia tai diem R ,cat tia doi cua tia DC tai diem S. Chung minh cac tam giac APS, AQR CAN.
cho tam giac ABC khong can co AD la phan giac.tren tia doi tai BA lay E.tren tia doi tia CA lay E sao cho BE=BC=CF,BF cat CE o I.Duong thang qua I song song AD cat AC o K,duong thang qua c song song voi AB cat nhau o P
b,cm BF,CE la pgiac cac goc CBP va BCP
c,o la giao diem cua AD va BP.cm PI song song AO
d,cm AB=CK
cho tam giac ABC co goc ABC=30do va goc 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 AC va CE
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 hinh vuong ABCD ,E nam tren tia doi cua CB sao cho CE=CD;F thuoc tia doi cua CD sao cho CF=CB.AE cat CD tai M;AF cat BC tai N. ve hinh vuong BCFI.chung minh AN vuong goc voi EI