1. Tren 1 duong thang xy lay 4 diem phan biet A,B,C,D hay chi ra cac tia doi nhau 

2. cho 10 diem trong do khong co ba diem thang hang . Cu qua hai diem ta ve duoc 1 duong thang . Hoi co tat ca bao nhieu duong thang?

3. cho n diem trong do khong co ba diem nao thang hang . Cu qua hai diem trong so cac diem do ve duoc 1 duong thang. Biet rang co 435 duong thang tao thanh .Tim n?

Tren duong thang x,y lay o.Lay diem a thuoc tia ox,B thuoc tia oy sao cho OA=2cm;OB=2oa

A)Tinh do dai doan AB?

B)Goi Yla trung diem cua OB.Chung minh O la trung diem cua doan thang AI

C) Tren duong thang xy lay 100 diem diem phan biet(khac O,A,B,I).Noi 2 diem ta duoc mot doan thang.Hoi co bao nhieu duong thang tao thanh?

giup minh voi! HELP ME!!!!!

trong mat phang cho 10 diem phan biet, trong do khong co 3 diem nao thang hang.Hoi co the ve duoc bao nhieu tia, bao nhieu doan thang, bao nhieu duong thang? (neu trong diem phan biet do co 5 diem thang hang thi ve duoc bao nhieu tia, bao mhieu doan thang, bao nhieu duong thang).

cho 1000 diem phan biet trong do co dung 3 diem thang hang hoi co bao nhieu duong thang tao thanh boi 2 trong 1000 diem do

Cho 50 diem phan biet, trong do co 5 diem thang hang. Qua 2 diem bt ky ta ke duoc 1 duong thang. Hoi co tat ca bao nhieu doan thang nhan 2 trong 50 diem do lam dau mut.

tinh tong 2011 cac so tu nhien le dau tien 

tren duong thang d lay 2012 diem phan biet 

tinh so doan thang tren duong thang d duoc tao thanh tu 2012 cac diem do

Cho 4 diem A;B;C;D phan biet cung nam tren duong thang xy. Tao thanh bao nhieu tia?

cho hai duong thang a va b song song. tren duong thang a lay 10 diem phan biet, tren duong thang b lay 15 diem phan biet. hoi co the ve bao nhieu duong thang phan biet  qua 2 trong cac diem da cho ?