cho 3 diem A B C bat ki va mot diem O khac diem A B C . co bao nhieu tia goc O va di qua mot trong ba diem A B C
Những câu hỏi liên quan
cho duong thang xy.tren duong thang xy co 2017 diem,3 diem a,b,c khong thuoc duong thang xy va ko thang hang va bat ki diem nao tren dương thang xy deu khong thang hang voi hai trong ba diem a,b,c.qua hai diem bát ki nguoi ta ke mot duoc thang.hoi co bao nhieu duong thang?
neu diem O nam tren duong thang xy thi
a) diem ..... la goc chung cua ox va oy
b) diem ..... nam giua 1 diem bat ki khac O cua tia ox va 1 diem bat ki khac O cua tia oy
cho diem O nam ngoai duong thang d. tren dung thang d lay ba diem A,B,C saocho AB=6cm;AC=2cm
a tinh BC
b gia su goc OAB=180 do;tinh goc OAC
c tren dung thang d lay them 2015 diem phan biet [khac A,B,C] hoi co bao nhieu goc co dinh O va canh di qua 2 diem thuoc dung thang d
LG
a) Trên tia AB có :
AB=6cm
AC=2cm
=>AB>AC(6>2)
=>Điểm C nằm giữa hai điểm còn lại
=> AC+CB=AB
2+CB= 6
CB= 6-2
CB= 4
Vậy CB bằng 4 cm
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cho mot duong thang a.ve 1 dem a thuoc duong thang a.ve mat duong thang b di qua diem a.cho diem b nam tren duong thang b.ve mot duong thang c di qua diem a va b.cho diem c nam giua diem a va diem b.hoi diem c nam o duong thang nao
Ve duong thang va mn cat nhau tai O . Trên tia Oxy lay diem A, tren tia Oy lay diem C( A,C khac O ). Trên tia doi cua tia Ox lay diem B . Lay diem Q bat ki , không thuoc mn . Hay ve ba diem B,Q,P thang hang sao cho P thuoc mn
Cho ∆ ABC can tai A. Cac tia phan giac cua goc B va goc C cat nhau tai O. Qua A ke duong thang D song song voi BC. Tia BO cat AC va D lan luot tai M va D. Tia CO cat AB va D lan luot tai N va E.
a, c/m ∆ACN =∆ABM
b, c/m A la trung diem cua doan thang BE
c , c/m ba duong thang AO , CE , CD cung di qua mot diem
Cho ∆ ABC can tai A. Cac tia phan giac cua goc B va goc C cat nhau tai O. Qua A ke duong thang D song song voi BC. Tia BO cat AC va D lan luot tai M va D. Tia CO cat AB va D lan luot tai N va E.
a, c/m ∆ACN =∆ABM
b, c/m A la trung diem cua doan thang BE
c , c/m ba duong thang AO , CE , CD cung di qua mot diem
Bài làm
a) Ta có tia phân giác của góc \(\widehat{ABC}\)
=> \(\widehat{B}_1=\widehat{B_2}\)
Ta có tia phân giác của góc \(\widehat{ACB}\)
=> \(\widehat{C}_1=\widehat{C_2}\)
Mà \(\widehat{ABC}=\widehat{ACB}\)( Tam giác ABC cân tại A )
=>\(\widehat{B}_1=\widehat{B_2}=\widehat{C_1}=\widehat{C_2}\)
Xét tam giác ACN và tam giác ABM có:
\(\widehat{B}_1=\widehat{C_1}\)( Chứng minh trên )
AB = AC ( tam giác ABC cân tại A )
\(\widehat{BAC}\)là góc chung
=> Tam giác ACN = tam giác ABM ( g.c.g ) ( đpcm )
b) ~ Mik nghĩ đề bài bn sai ở chỗ câu b. pk là A là trung điểm của DE mới phải ~
Vì \(\widehat{B}_1=\widehat{C_1}\)( Chứng minh trên )
Ta có: \(\widehat{B}_1\)đối diện với cạnh AD ( 1 )
Vì \(\widehat{C_1}\)đối diện với cạnh EA ( 2 )
Từ ( 1 ) và ( 2 ) => AD = AE
=> A là trung điểm của DE ( đpcm )
# Hok_tốt #
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tren duong thang xy lay them 2012 diem M1, M2,M3,..,M2012 phan biet voi nhau va phan biet voi cac diem A, B,O,I co the ve duoc bao nhieu goc dinh C ma cac canh la cac tia goc C va di qua cac diem da cho tren duong thang xy
Cau 5: Trong cac khang dinh sau, khang dinh nao dung, khang dinh nao sai?1.Ba diem phan biet la ba diem thang hang.2.Voi ba diem phan biet luon co hai diem nam ve cung phia doi voi diem con lai.3.Voi ba diem thang hang phan biet luon co hai diem nam khac phia voi diem con lai.4.Voi ba diem A,B,C thang hang thi diem B luon nam giua hai diem A,C.5.Co mot va chi mot duong thang di qua hai diem (phan biet) cho truoc.6.Hai duong thang phan biet thi song song voi nhau.7.Hai tia chung goc thi cung nam...
Đọc tiếp
Cau 5: Trong cac khang dinh sau, khang dinh nao dung, khang dinh nao sai?
1.Ba diem phan biet la ba diem thang hang.
2.Voi ba diem phan biet luon co hai diem nam ve cung phia doi voi diem con lai.
3.Voi ba diem thang hang phan biet luon co hai diem nam khac phia voi diem con lai.
4.Voi ba diem A,B,C thang hang thi diem B luon nam giua hai diem A,C.
5.Co mot va chi mot duong thang di qua hai diem (phan biet) cho truoc.
6.Hai duong thang phan biet thi song song voi nhau.
7.Hai tia chung goc thi cung nam tren mot duong thang.
8.Hai tia chung goc thi doi nhau
9.Neu diem M nam giua diem A,B thi no la trung diem cua doan thang AB.
10.Neu MA=MB thi M la trung diem cua doan thang AB.
11.Neu MA+MB= AB va MA=MB thi M la trung diem cua doan thang AB.
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