hoi3 diem A,B,C co thang hang ko,neu a/AB=1/2,BC=1/3,CA=1/6(cm)
Bài 1 : cho trước 6 điểm A B C D E F vẽ các đường thẳng đi qua các cặp điểm a) neu trong 6 diem ko co 3 diem nao thang hang thi se ve duoc bao nhieu duong thang b) neu trong 6 diem co dung 3 diem thang hang thi se ve duoc bao nhieu duong thang
Cho 20 diem trong do cu qua 2 diem ta ke 1 duong thang
a/Neu khong co 3 diem nao thang hang thi ta ke duoc bao nhieu duong thang
b/neu co dung 5 diem thang hang thi ke duoc bao nhieu duong thang
a) ta có 20*19:2=.... (tự tính)
b) ta có 20*19:2-5*4/2=.......(tự tính)
cho 100 diem noi tung cap 2 diem trong 100 diem do thanh cac doan thang tinh so doan thang tao ra nếu trong 100 điểm đó có:
a,ko co 3 diem nao thang hang
b,co dung 5 diem thang hang
c,neu tao ra 105 doan thang thi can bao nhieu diem
3 diem A, B, C co thang hang ko? Biet
AB= 5 cm, AC= 2cm va CB= 3 cm
co tat ca 25duong thang ko co 3 diem nao thang hang
a qua 2 duong thang lai ve duoc 1 duong .hoi co tat ca bao nhieu duong ?
b qua 5 diem ve duoc 5 duong hoi co tat ca bao nhieu duong?
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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Phat bieu nao dung, phat bieu nao sai?
1/ Co duy nhat mot duong thang di qua 2 diem cho truoc.
2/ Doan thang AB la hinh gom tat ca cac diem nam giua 2 diem A va B
3/ Co 3 diem M, A, B, neu co MA = MB thi M la trung diem cua doan thang AB
1/ đúng
2/ đúng
3/sai thiếu điều kiện M,A,B thẳng hàng
cho truoc 6 diem a,b,c,d,e,g.ve cac duong thang di qua cac cap diem t rong do ;a)6 diem da cho ko co 3 diem nao thang hang ;b)6 diem da cho co nhung diem nao thang hang
cho 150 diem trong do ko co 3 diem nao thang hang cu 2 diem ke 1 doan thang .hoi co tat ca bn doan thang
Ta có:
CỨ 1 điểm thì nối được với 149 đoạn thẳng còn lại nối được 149 đoạn thẳng
=> nối được: 150.149 (đoạn thẳng)
Nhưng nếu tính như vậy thì 1 đoạn thẳng sẽ được tính 2 lần
Vậy vẽ được số đoạn thẳng là:
150.149/2=75.149=11175(đoạn thẳng)