Cho tam giac ABC co AB=AC. Goi M la trung diem doan thang BC
a) chung minh tam giac AMB= tam giac AMC
b) chung minh AM la tia phan giac cua goc BAC
c) duong thang di qua B va vuong goc voi BA cat duong thang AM tai I. Chung minh CI vuong goc voi CA
CAC BAN GIUP MINH VOI
CAM ON NHIEU NHIEU NHA!!!!
Cho tam giac A,B,C vuong tai A ( AB nhỏ hơn AC ) . Kẻ AH vuông tại BC, H thuoc BC. Tren tia doi lay diem M sao cho HM = HA
A ) Chung minh : ∆ABH = ∆ MBH
B) Goi I la trung diem cua BC, qua C ke duong thang vuong tai AC, duong thang nay cat tia AI ở D . CM: AB=CD
C) Chung minh : BC // DM
cho tam giác abc có ab< ac,tia phan giac cua goc a cat bc tai e.tren ac lay diem d sao cho ab=ad.bd cat ae tai i.n la giao diem cua ab và de.m la trung diem cua nc. chung minh a,i,m thang hang
Cho tam giac ABC tia phan giac cua goc A cat duong trung truc cua BC tai I. Qua i ke cac duong vuong goc voi duong thang AB va AC theo thu tu la H va K. CMR:
a)AH=AK
b)BH=CK
c)AK=AC+AB/2 va CK= AC-AB/2
cho tam giac ABC vuong tai A ,co AC=2AB.lay D la trung diem cua AC .dung AH,CK vuong goc voii BC.
a) cm; goc ABC = goc CDK va tam giac AHB = tam giac CKD
b) cm : DA= DC =DH va KH = KC
c) goi I la trung diem cua BD . Cm: tam giac AHI = tam giac KHI tu do tinh soo do goc IHK
d ) duong thang di qua A song song voi BC cat DK tai M. cm : H , I , M thang hang
e) duong thang AI cat BC tai N . cm : NK =
Cho tam giac ABC co AB=AC tia phan giac cua goc A cat BC tai M .Chung minh
tam giac ABC=TAM GIAC ACM
M la trung diem cua BC
AM vuong goc voi BC
cho tam giac ABC can tai A. Goi M la chung diem cua BC .Goi E,F thu tu la chan cac duong vuong goc ke tu M den AB vaAC.Chung minh ME=MF AE=AF ,AM vuong goc EF ,EF//BC
Cho tam giac ABC vuong tai A va M la trung diem AB ke MN vuong goc BC tai N Tren tia doi tia AB lay D sao cho AD=BN Ke ME vuong goc CD tai E Cac doan thang DN va ME cat nhau tai K Goi I la trung diem cua doan thang DK Tinh so do goc CIM
Cho tam giac ABC vuong tai A co tia phan giac BD(\(D\in AC\)).Tren canh BC lay diem E sao cho AB=BE.Tren tia doi cua tia AB lay diem F sao cho AF=EC.Goi I la giao diem cua BD va FD.Chung minh rang
a)CM ΔABD=EBD, \(DE\perp BC\)
b)BD la duong trung truc cua doan AE
3)3 diem F,D,E thang hang
4)Tinh do dai doan FC khi AC = 5cm ,ACB = 30 do
