Cho <xOy Khác goc bet, Ot la TPG cua < xOy. Tren tia Ox lay A, tren tia Oy lay B ( A;B khac 0 ). Tia OF cat Ab tai C
a) CM: Tam giac AOC= tam giac BOc va tinh <ACO
b) Tren OC lay H nam giua O va C , dg thang AH cat OY tai D , dg thang BH cat OC tai E. CM HO la TPG cua <EHD
c)Dg thang CE cat AB tai M. dg thang CD cat BH tai N; MN cat Ot tai E. CM F la trung diem cua MN
Bai 5: Cho goc xOy nhon, Ot la tia phan giac cua xOy. Tren tia Ot lay diem H, qua H ve duong thang vuong goc voi Ot cat Ox tai A, cat Oy tai B.
a/ Chung minh \(\Delta AHO=\Delta BHO\)
b/ Tren tia Ax lay diem C, tren tia By lay diem D sao cho AC=BD. Chung minh AD=BC
c/ CD cat tia ot tai K. Chung minh AB / / CD
mn giup em vs ak
cho tam giác ABC co góc A=90 do va ab=ac tren canh ab va ac lay d va e sao cho ae=ad tu a va d ke dg thang vuong goc vs be cat bc tai m va n tia md cat tia ca o I cm a la trung diem cua ci va cm=mn
Cho goc xOy khac goc bet tren canh Ox lay diem B sao cho OA=OB. Ve hai canh tron tam A va Tam B cung ban kinh cat nhau tai diem C nam trong goc xOy
1 c/m ∆AOC=∆BOC
C/to Oc la tia phan giac cua goc xOy
Goi M la trung diem cua AB. Chung minh ba diem O, M,C thang hang
Cho goc xOy khac goc bet. Tren tia phan giac Ot cua goc xOy lay diemC,ke duong thang d vuong goc voi ot tai C,va cat Ox,Oy lan luot taiA,B.Chung minh rang:
a,Tam giac AOC bang tam giac BOC
b, OA = OB
c,Lay diem d thuoc tia Ot(D khac C).Chung minh AD bang BD, goc OAD bang gocOBD
cho tam giac abc can tai a. lay d tren bc , tren tia doi tia cb lay e sao cho ce=bd. cac duong thang vuong goc voi bc tai d va e lan luot cat cac duong thang ab va ac theo thu tu tai m va n. i la giao diem cu mn va bc. chung minh: a, i la trung diem cua mn
Cho goc nhon xAy. Tren tia Ay lay diem C sao cho AB=AC (B va C khac A). Duong thang vuong goc voi Ax tai B va duong thang vuong goc voi goc Ay tai C cat nhau o diem M.
a, c/m ∆ABM =∆ACM
b, tia CM cat Ax tai diem N . chung minh CM<MN
Bai 2:
Cho ∆ ABC vuong tai A ,phan giac goc B va phan giac goc C cat nhau tai diem O. Goi E va F thu tu la hinh chieu cua O tren AB va AC.
a, c/m ∆AEO=∆AFO
b, cho AB=6cm, AC =8cm. Tinh do dai doan thang AE
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 duong cao ah tren tia ac lay diem m sao cho ac bang cm.keo dai ah cat bm tai e
a, cmr hb bang hc
b,cmr tam giac ebc can
c,hai dg thang ab va ce cat nhau tai k.cmr.e la trong tam cua tam giac akm
d,cmr..am - ab lon hon em - eb
cho goc xOy khac goc bet ,Ot la phan giac. tren Ot lay H qua H ke duong thang vuong goc Ot cat Ox tai A,Oy tai B.
chung minh a)AH=BH
b)tren Ax lay C,tren By lay D sao cho AC=BD.CHUNG MINH AD=BC
c)chung minh AB//CD
d)chung minh AB,BC,OH cung di qua mot diem
