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 ABC, co AC<AB, M la trung diem BC, ve phan giac AD. Tu M ve duong thang vuong goc voi AD tai H, duong thang nay cat tia AC tai F, cat AB tai E. Chung minh rang:
a) Δ AFE can
b) Ve duong thang Bx//EF, cat AC tai K. Chung minh rang: KF=BE
c) Chung minh rang: AE= \(\dfrac{AB+AC}{2}\)
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 C góc B=40 do tia phan giac goc A cat BC tai D tren canh AB lay diem E sao cho EA=AC chứng minh tam giac ADE là tam giac vuong
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 giác ABCco A=6cm,BC=8cm ,CÁ=10cm
a, Dinh dang tam giac ABC
b, Tren tia doi cua tia BC lay diem D sao cho BD=BC .Chung minh tam giac ACD can
c,Tren AB lay diem M .Chung minh rang MC=MD va MB la tia phan giac cua goc CMD
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 , ve diem M laqtrung diemcua BC. Trentia doi cua tia Ma lay diem D sao cho MA=MD.
a) Chung minh:tam giac ABM=tam giac DCM b) Chung minh:AB// DC C) Ke BE vuong goc AM (E thuoc AM), CFvuong goc DM (F thuoc DM). Chung minh: Mla trung diem cua EF [ve hinh va giai bai tap ho to nhe]