cho tam giac ABC v uong tai A (AB < AC ) , ke AH vuong goc voi BC tai H . tren canh AC lay diem I sao cho AH =AI . qua I ke duong thang vuong goc voi A C , cat BC tai D
a, CMR : tam giac AHD = tam giac AID va` AD la tia phan giac cua ∠HAC
b, tia ID cat tia AH tai M . CMR △MCD can
c, go.i N la` trung diem cua MC . CMR AN,MI,BC do^`ng quy
1. cho tam giac ABC can tai A, ve diem M, Nbat ki tren duong trung truc ca doan thang BC.CM:
a,tam giac MBCcan tai M
b, MNC=MNB
2.cho tam giac ABC cao M la trung diem cua canh BC. qua B ke duong thang Bx \\ AC, qua C ke Cy \\ AB. giao diem cua Cy, Bx la D. CM: A, D, M thang hang.
3. do dai 2 canh goc vuong cua mot tam giac vuong ti le voi 7 va 24. chu vi tam giac bang 112. tinh do dai canh huyen.
4.cho tam giac ABC can tai A, canh day nho hon canh ben. duong trung truc cua AC cat BC tai M. tren tia doi cua AM lay N \ AN = BM.
a, CM: 2 goc AMC va BAC bang nhau
b, CM: CM = CN
c, de CM vuong voi CN hi tam giac ABC phai co them dieu kien gi?
5. cho tam giac ABC deu. tren tia doi cua tia phan giac goc BAC lay D \ AD = AB. tinh cac goc cua tam giac DBC.
cho tam giac ABC vuong tai A . Ve duong cao AH, tren AH lay D, tren tia doi cua HA lay E sao cho HE bang AD. Duong thang vuong goc voi AH tai D cat AC tai F .CMR: EB vuong goc voi EF
cho tam giac ABC can tai A( goc A < 90 do) cac duong cao BD, CE( D thuoc AC, E thuoc AB ) cat nhau tai H
a) chung minh tam giac ABD= tam giac ACE
b) chung minh tam giac BHC la tam giac can
c) so sanh HB va HD
d) tren tia doi cua tia DH lay diem M sao choMH=NH. Chug minh duong thang BN,AH,CM dong quy
cho tam giac abc vuong tai a. tren canh ab lay d, tren canh ac lay e sao cho ad=ae, cac duong thang vuong goc ve tu a va e voi cd cat bc tai g va h. duong thang eh va duong thang ab cat nhau o m. duong thang ve tu a songsong voi bc cat hm tai i. cmr: tam giac acd bang tam giac ame
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
bai 1co tam giac abc can tai a tren tia doi cua cac tia bc va cb lay hai diem d va e sao cho ce = bd goi m la trung diem cua bc tu b va c ke bh vuong goc voi ad va ck vuong goc voi ae .cm 3 dt bh ck va am cung di qua mot diem
bai 2 cho tam giac abc vuong tai a goc c bang 30 do duong cao ah tren doan hc lay diem d sao cho hd=hb tu c ke ce vuong goc voi ad cmr
a, tam giac abd deu
b,eh song song voi ac
bai 3 cho tam giac abc co goc a = 90 do qua a ke dt d tu b va c ke bd vuong goc voi dt d va ce vuong goc voi dt d tinh do dai de theo bd va ce
bai 4 cho tam giac abc vuong tai a hai duong phan giac bm va cn tu m va n ke mmphay va nnphay vuong goc voi bc cmr goc mphayanphay bang 45 do
Cho tam giac ABC can tai A tren tia doi cua tia BC lay diem D, cua CB lay diem E sao cho BD= CE
a)CMR tam giac ABD = tam giac ACE
b)Ke BM vuong goc AD, CN vuong goc AC. CMR tam giac ABM = ACN
c)CMR MN song song BC
d)MB keo dai cat NC keo dai tai O. CMR AO la tia phan giac cua goc DAE
e) AO keo dai cat BC tai H. Gia su AH = 1/2 AD. Tinh ca goc cua tam giac ADE
( chu y lam cau cuoi truoc ho minh cac ban nhe.:D)
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