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.
Cho duong tron ( O ; 5cm) va diem M. neu OM = 5cm thi :
cho hinh ve 2 duong tron tam O, ban kinh 4cm mot diem A thuoc ( O;4cm) thi : OA bang bao nhieu cm
cho 2 diem M va N nam Cung phia voi A , nam cung phia doi voi B . Diem M nam giua A va B . biet AB =3cm,BN=1cm.chung to rang:
a, bon diem ABMN thang hang
b, diem N la trung diem cua doan MB
c , ve dung tron tam N di qua B va duong tron tam A di qua N , chung cat nhau tai C tinh chu vi tam giac CAN
cho 2 diem M va N nam Cung phia voi A , nam cung phia doi voi B . Diem M nam giua A va B . biet AB =3cm,BN=1cm.chung to rang:
a, bon diem ABMN thang hang
b, diem N la trung diem cua doan MB
c , ve dung tron tam N di qua B va duong tron tam A di qua N , chung cat nhau tai C tinh chu vi tam giac CAN
cho hai diem A,B cach nhau 3cm . ve duong tron ( A, 2,5cm ) va duong tron ( b , 1,5cm ) hai duong tron cat nhau tai C va D .
tinh CA va DB
cho đường tròn tâm o bán kính r =4cm va doan thang OA=5cm . chung to diem A nam ben ngoai duong tron (O;4cm)
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.
1.ve duong thang xy.lay diem O tren duong thang xy.lay diem M thuoc tia Oy.lay diem N thuoc tia Ox.
a)viet ten 2 tia doi nhau goc O.
b)trong ba diem M,O,N thi diem nao nam giua 2 diem con lai.