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
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 Ot la tia phan giac cua goc nhon xoy. Tren tia Ox lay diem A, tren tia Oy lay diem B saocho OA=OB. Tren tia Ot lay diem M sao cho OM>OA.a) Chung minh tam giac AOM= tam giac BOM. b) Goi C la giao diem cua tia Am va tia Oy. D la giao diem cua BM va Ox. Chung minh rang: AC=BD. c) Noi a voi B, ve duong thang d vuong goc voi AB tai A. Chung minh:d// Ot
a: Xét ΔOAM và ΔOBM có
OA=OB
\(\widehat{AOM}=\widehat{BOM}\)
OM chung
Do đó: ΔOAM=ΔOBM
b: Xét ΔOAC và ΔOBD có
\(\widehat{AOC}\) chung
OA=OB
\(\widehat{OAC}=\widehat{OBD}\)
Do đó; ΔOAC=ΔOBD
Suy ra: AC=BD
Cho goc nhon xOy co Ot la tia phan giac. Lay diem A tren tia Ox, diem B tren tia Oy sao cho OA=OB. Ve doan thang AB cat tia Ot tai M. a) Chung minh: tam giac AOM=tam giac BOM, b)chung minh AM=BM, c) chung minh: OM vuong goc voi AB
Cho goc xOy khac got bet co tia phan giac Ot. Lay diem A thuoc tia Ox, ve tia Am // Oy ( tia Am nam trong goc xOy )
a/ Chung minh goc xAm = goc xOy
b/ Ve tia phan giac An cua goc xAm. Cm: An // Ot
c/ Ve tia Ah vuong goc Ot tai H. Cm AH la tia phan giac cua goc OAm
cho goc xoy =50 do. lay diem A tren tia ox . tren cung 1 nua mat phang bo ox chua tia oy, ve tia ot sao cho oy cat nhau tai B va goc oAt =80 do. goi at' la tia phan giac cua goc xAt
a) chung minh At'song song voi Oy
b) tren nua mat phang ko chua diem A bo duong thang oy ve tia Bn song song Ox
ta có\(\widehat{OAt}+\widehat{tAx}=\widehat{OAx}\)
thay\(80^o+\widehat{tAx}=180^o\)
\(\widehat{tAx}=180^o-80^o=100^o\)
vid tia At' là tia phân giác của tAx
\(\Rightarrow\widehat{tAt'}=\widehat{t'Ax}=\frac{\widehat{xAt}}{2}=\frac{100^o}{2}=50^o\)
\(\Rightarrow\widehat{xAt'}=\widehat{xOy}=50^o\)
hai góc \(\widehat{xAt'}\)và\(\widehat{xOy}\)ở vị trí đồng vị bằng nhau
\(\Rightarrow Oy//At'\)
b)
cho goc xoy va tia phan giac oz, tren tia ox lay diem a, tren tia oy lay diem b sao cho oa=ob. lay diem i tren tia oz (i#o)
a/ chung minh tam giac oai bang tam giac obi
b/doan thang ab cat oz tai h. chung minh h la trung diem cua ab
c/chung minh ab vuong goc voi oz
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
cho goc Xoy nho hon 90 do va tia phan giac Ot lay A tren Oz va M la trung diem cua OA tu M ke duong thang vuong goc voi OA cat OY o B chung minh tam giac ABO can va Ox song song voi AB
