biet ba diem a,b,c thang hang diem c nam giua hai diem con lai co the chi do do dai cua hai doan thang ma biet dc ba do dai ab,ac,bc ko giai thich cach lam cua ban
ve tuy y 3 diem A , B , C thang hang . Lam the nao de chi do 2 lan ma biet duoc do dai cua cac doan thang AB , BC , CA
Cho diem C nam giua hai diem A va B, biet AB = 6cm. Goi M va N lan luot la trung diem cua cac doan thang AC va BC.
a) Tinh do dai doan thang MN.
b) Hay neu cach chon diem C de cho do dai doan thang MN gap 3 lan do dai doan MC.
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.
ve goc xOy. ve tia Oz man giua hai tia Ox,Oy. lam the nao chi de do hai lan ma biet duoc so do cua ca ba goc xOy, yOz,xOz. co may cach
cho tia ox goi a la mot diem tren tia ox sao cho oa = 3cm tren tia ax lay diem b sao cho ab=5cm tren tia doi cua tia bx lay diem c sao cho bc= 4cm
a.trong ba diem a ,b,c diem nao nam giua hai diem con lai? vi sao?
b. tinh do dai doan thang AC
c. diemC co phai la trung diem cua doan thang OB hay khong? VI SAO?
Tren tia Ox cho 4 diem A,B,C,D.Biet rang A nam giua B va C;B nam giua C va D; OA=7cm; OD=3cm; BC=8cm; va AC=3BD
a,Tinh do dai AC.
b,Chung to rang diem B la trung diem cua doan thang AD
CACH LAM NHA
Cho doan thang AC = 5cm. Diem B nam giua A va C sao cho BC = 3cm
a) Tinh do dai doan thang AB
b) Tren tia doi cua tia BA lay diem D sao cho BD = 3AB. Diem C co la trung diem cua BD khong?