Cho \(\Delta ABC\) co \(\widehat{A}=90^o\) .Ke BI la phan giac \(\widehat{ABC}\) ( I thuoc AC ).Lay D tren canh BC sao cho BA=BD
a.CM:\(\Delta ABI=\Delta DBI\)
b.CM:I ID vuong goc BC
c.Lay E thuoc tia BA sao cho BE=BC.CMR: D,I,E thang hang
d.\(\Delta ABC\) bo sung them dieu kien gi de \(\Delta IEC\) deu
cho \(\Delta ABC\)vuong tai A, phan giac goc B cat AC tai I . tren canh BC lay diem E sao cho AB=BE
a,CM: \(\Delta ABI=\Delta EBI\)va =>\(\widehat{BEI}\)= 90 do
b, 2 tia BA va EI cat nhau tai D . CM:\(\Delta AID=\Delta EIC\)va =>\(\Delta IDC\)can
c, CM: AE//DC
cho tam giac ABC co AB<BC. Tren tia BA lay diem D sao cho BC=BD.Tia phan giac cua goc B cat canh AC o E.Goi K la trung diem cua DC
a)Chung minh:tam giac BED = tam giac BEC
b)Chung minh:EK vuong goc DC
c)Chung minh:B,K,E thang hang
d)Ke AH vuong goc DC (H thuoc DC).Tam giac ABC can them dieu kien gi de goc DHA=45 do
Bai 2:cho \(\Delta ABC\) co AB=AC;M la trung diem BC
a/ chung minh \(\Delta AMB=\Delta AMC\)
b/ Chung minh \(AM\perp BC\)
c/\(\Delta ABC\)co goc A=\(^{40^o}\). Tinh goc B
Bai 3: Cho \(\Delta ABC\)vuong tai A, lay D thuoc canh BC sao cho BD=BA; tia phan giac go B cat canh AC o E
a/ Chung minh \(\Delta ABE=\Delta DBE\)
b/ Chung minh goc BEA= goc BED.
c/ Ve tia \(Ex\perp BE\)tai E. Chung minh Ex / / AD
Bai 4: Cho \(\Delta ABC\)co AB= AC, H la trung diem BC
a/ Chung minh \(\Delta ABH=\Delta ACH\)
b/ Tren canh AB lay diem M, tren canh AC lay diem N sao cho MA=AN
c/ Goi E la giao diem cua AH va MN. Chung minh \(\Delta AME=\Delta ANE\)
d/ Chung minh MN / / BC
Moi ng giup em vs ak. E dang can gap lam. Ai lam dung va nhanh nhat e se tick cho ak. tks mn nhieu. <3
cho tam giác ABC (AB<AC) . TRen tia BA lay diem D sao cho BD = BC . Noi cvoi D . Tia phan giac cua goc B cat canh AC va CD theo thư tư ở E và I . CHỨNG MINH :
a, \(\Delta BID=\Delta BIC\)
b, ED=EC
c, kẻ AH vuông góc voi CD tại H , C/M: AH//BI
d, biết số đo \(\widehat{ABC=70^O}\), TÍNH \(\widehat{BCD},\widehat{DAH}\)
cho tam giac abc vuong tai a co bd la tia phan giac cua abc d thuoc ac lay diem e tren bc sao cho be=ba chung minh de vuong bc
Cho \(\Delta ABC\)vuong o A. Tren BC lay D sao cho BD=BA. Duong thang \(\perp\)BC tai D cat AC o E.
a) So sanh AE va DE
b) Tia phan giac cua goc ngoai o C cat BE o K . Tinh goc BAK !?!?
\(cho\Delta ABC\)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 A = 90 do. Ve Tia phan giac Bd cua goc B ( D thuoc AC ). Tren canh BC lay E cho BE = BA
a) so sanh do dai doan AD va DE, so sanh goc EDC va ABC
b) cm AE vuong goc voi BD
Cho tam giac ABC vuong goc tai A . Ke BD la tia phan giac cua goc ABC (D thuoc AC). Tren canh DC lay diem E sao cho BE = BA
a) Chung minh tam giac ABD= tam giac EBD
b) Chung minh DE = DA va DE vuong goc BC
c) chung minh BD la duong trung truc cua doan AE
*dang can gap :c
