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cho 4 diem A,B,C,D thuoc duong tron tam O sao cho AB=CD chung minh rang tam giac AOD = tam giac COD
Cho 4 diem thoc duong tron tam o biet ab= cd a)tam giac aob=tam giac cod
B)aob=cod
Chao cac gia su va cac ban.Minh co 1bai toan chua lam duoc.Nhu lan truoc,minh da dat cau hoi ve hinh hoc.Lan nay minh xin dat mot cau nua,mong moi nguoi giup minh bai toan nay :Cho tam giac ABC vuong tai A,co goc B 60 do.a, Tinh so do goc C va so sanh do dai 3canh cua tam giac ABCb,Ve BD la tia phan giac cua goc ABC(D thuoc AC).Qua D ve DK vuong goc voi BC(K thuoc BC) .Chung minh:tam giac BADtam giac BKDc,C/minh :tam giac BDC can va K la trung diem BCd,Tia KD cat BA tai I.Tinh do dai canh ID bie...
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Chao cac gia su va cac ban.Minh co 1bai toan chua lam duoc.Nhu lan truoc,minh da dat cau hoi ve hinh hoc.Lan nay minh xin dat mot cau nua,mong moi nguoi giup minh bai toan nay :
Cho tam giac ABC vuong tai A,co goc B =60 do.
a, Tinh so do goc C va so sanh do dai 3canh cua tam giac ABC
b,Ve BD la tia phan giac cua goc ABC(D thuoc AC).Qua D ve DK vuong goc voi BC(K thuoc BC) .Chung minh:tam giac BAD=tam giac BKD
c,C/minh :tam giac BDC can va K la trung diem BC
d,Tia KD cat BA tai I.Tinh do dai canh ID biet AB=3cm(lam tron ket qua den chu so thap phan thu nhat).
Neu ai, gia su co the tra loi duoc cau hoi nay thi xin nhan tin lai cho minh a.Minh xin cam on nhieuuuuuuuu(ve hinh nua nhe! )
cho tam giac ABC co AB<AC.Tren tia doi cua tia CA lay diem D sao cho CD=AB.GOi P,Q la trung diem cua AD,BC va I la giao diem cua cac duong vuong goc voi AD BC tai P va Q
A)ching minh tam giac AIB= tam giac DIC
B) ching minh AI la tia phan giac cua goc BAC
c) Ke IE vuong goc voi AB,chung minh AE=1/2AD
ai lam duoc co ve hinh day du cho 10 tick nha
1 cho tam giac abc can a , goc a bang 40 do lay d khac phia b so voi ac thoa man goc cad bang 60 do goc cad bang 80 do chung minh bd vuong goc voi ac2 cho tam giac abc vuong can a . d la diem bat ki tren ab. tren nua mat phang bo ab tu c ve tia bx sao cho goc abx bang 135 do. duong thang vuong goc voi dc ve tu d cat bx o e . chung minh tam giac dec vuong can3 cho tam giac abc can b goc abc bang 80 do , i la diem trong tam giac sao cho goc iac bang 10 do, ica bang 30 do tinh goc abi4 cho tam gia...
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1 cho tam giac abc can a , goc a bang 40 do lay d khac phia b so voi ac thoa man goc cad bang 60 do goc cad bang 80 do chung minh bd vuong goc voi ac
2 cho tam giac abc vuong can a . d la diem bat ki tren ab. tren nua mat phang bo ab tu c ve tia bx sao cho goc abx bang 135 do. duong thang vuong goc voi dc ve tu d cat bx o e . chung minh tam giac dec vuong can
3 cho tam giac abc can b goc abc bang 80 do , i la diem trong tam giac sao cho goc iac bang 10 do, ica bang 30 do tinh goc abi
4 cho tam giac abc can a co goc a bang 100 do , bc =a, ac =b ve phia ngoai tam giac abc ve tam giac abd can d co goc adb bang 140 do tinh ch vi tam giac adb theo a,b
ve hinh gium minh voi , xin mn day
Cho tam giac ABC can tai A.Tren canh AB lay diem D sao cho AD=BC.Qua D ve 1 duong thang song song voi BC,tren do lay DE=AB(E thuoc nua mat phang chua C,bo la duong thang AB). a) chung minh tam giac EDA=tam giac ABC; b) tinh so do goc DAE?;c) chung minh tam giac ACE deu
Cho tam giac ABC co AB=BC . Goi I la trung diem cua AB . Tren tia CI lay D sao cho D nam khac phia voi C so bo la doan thang AB
a/ c/m tam giac ADC=BDC
b/ suy ra CD la duong thang trung truc cua AB
{ ko can ve hinh nhung viet ro gium minh cai cam on nhieu }
Tam giac ABC can tai A tren canh AB lay diem E tren canh AC lay diem F sao cho BF=CE .goi O la giao diem cua ba duong trung truc cua tam giac .ABC.Chung minh O thuoc duong trung truc cua EF
cho tam giac abc can tai a ( a > 90 ) ve duong trung truc ab,ac cat canh nay o m,n va cat bc tai o,i a) tam giac aob,aic la tam giac gi
b) goi d la giao diem mo,ni , chung minh tam giac amd =and
c) chung minh d la truc tam cua 2 tam giac aob va aic
ve hinh day du ho minh nhe