cho 10 diem phan biet thuoc 1 duong thang d va 1 diem O nam ngoai duong thang ay
so tam co cac dinh la 3 trong 11 diem tren
Cho 2009 diem thuoc duong thang a va mot diem nam ngoai duong thang ay.Co bao nhieu tam giac co cac dinh la ba trong 2010 diem tren?
Gọi điểm nằm ngoài đường thẳng là D
Nối 2009 điểm thuộc a với D ta được 2009 đường thẳng
1 đường thẳng kết hợp với 1 đường thẳng được 1 tam giác ( cạnh còn lại là đường thẳng a)
1 đường thẳng kết hợp với 2008 đường còn lại được 2008 tam giác
Làm vậy với 2009 đường thẳng ta được 2009.2008 tam giác
Do số tam giác được tính 2 lần nên chỉ có
2009.2008:2= 2017036 tam giác
Cho P la so nguyen to lon hon 3 va 5p+1 cung la so nguyen to. Chung minh rang 7p+1 la hop so
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
1. Lay 4 diem A, B, C, D trong do khong co 3 diem nao thang hang. Ke cac duong thang di qua cac cap diem. Co bao nhieu duong thang tat ca? do la nhung duong thang nao?
2. Lay 4diem M,N,P,Q trong do 3 diem M,N,P thang hang va diem Q nam ngoai duong thang do. ke caacacc duong thang di qua cac cap diem. co bao nhieu duong thang phan biet? viet ten cac duong thang do
mong cac ban giai ho minh!
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.
ttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttttt
Tren duong thang d lay theo thu tu cac diem A1, A2, A3... A2000 va 1 diem B nam ngoai duong thang d. Co bao nhieu tam giac ma 3 dinh la cac diem noi B voi A1, A2, A3... A2000 ( giup voi, sao hong ai giup tui vay, help)
ve duong thang d khong di qua diem o . tren duong thang d lay 2014 diem phan biet . tinh so goc co dinh o va canh di qua 2 diem bat ki tren duong thang d
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 ?
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
co 100 diem A1,A2,...,A100 phan biet thuoc dg thg d va diem b nam ngoai dg thg d. Co bao nhieu tam giac co cac dinh la 3 trong 101 diem nêu tren