1) Cho diem A ( 1; -5 ). Tim toa do B biet A la anh cua B qua phep tinh tien theo vecto v = (2;1)
A. (6;-1) B. (1;-6) C(-3;-4) D. (3;4)
cho 99 diem tren mat phang trong do co 2 diem A va B cach nhau 3 cm. Moi nhom3 diem bat ki cua cac diem da cho bao gio cung co the chon ra 2 diem co khoang cach nho hon 1 cm. ve duong tron (A 1 cm)(B 1 cm). CMR trong 2 duong tron do co mot duong tron chuait nhat la 50 diem trong cac diem da cho.
bai 1 : cho 3 diem V, A , T thang hang . diem nao nam giua 2 diem con lai neu :
TV + VA = TA
bai 2 : tren 1 duong thang , hay ve 3 diem V , A , T sao cho TA = 1 cm , VA = 3 cm . hoi diem nao nam giua 2 diem con lai
cho doan thang AB=6cm. lay diem M nam giua A va B sao cho AM = 1/3 . tren tia MB lay diem I sao cho MI=1/2 AM .Hãy chung to rằng diem I ko la trung diem cua MB nhung I la trung diem cua AB
HElp me
cho 1/2 duong tron (O;A), M la 1 diem chuyen dong tren 1/2 duong tron sao cho AM<BM. Cla 1 diem tren tia AM sao cho AC = BM. Chung minh rang duong thang d vuong goc voi AM tai C luon qua 1 diem co dinh
1 . cho 4 diem A,B,C,D thang hang do :
ke ten cac truong hop 1 diem nam giua 2 diem con lai .
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?
1: cho diem O nam giua 2 diem A va B tren tia doi cua AO lay diem C sao cho OC = 5 cm . Biet OA =1 cm , OB = 2 cm . Hay so sanh AB va BC
1/Ve tia ox ;tren tia Ox ve diem A sao cho OA =a cm;ve diem B sao cho OB = 2 a (cm).
a/Trong 3 diem O ; A ;B diem nam giua 2diem con lai ?vi sao?Tinh AB theo a
b/Giai thich vi sao diem a la trung diem doan AB.
c/Goi I la trung diem doan AB. tinh OI theo a
Cho 20 diem,trong do co a diem thang hang,cu 2 diem,ta ve 1 duong thang.Tim a,biet ve duoc tat ca 171 duong thang
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