bon diem A;B;C;D ko nam tren duong thang a.chung to rang duong thang a ko cat hoc cat 3 hoac cat 4 cac doan thang AB;AC;AD;BC;BD;CD
cho 4 diem A;B;C;D khong nam tren duong thang a. biet doan thang AB khong cat a doan thang BC cat a.doan thang CD khong cat a. hoi doan thang AD co cat a hay khong
cho mot duong thang a.neu co 4 diem A;B;C;D khong nam tren duong thang a hoi duong thang a co the cat bao nhieu doan thang trong 6 doan thang AB;AC;AD;BC;BD;CD
cho 3 diem A;B;C khong thouc duong thang a.Biet rang duong thang a khong cat cac doan thang AB;AC.Hoi duong thang a co cat doan BC KO .vI SAO
Cho ba diem A,B,C khong thang hang ve duong thang a cat cac doan thang AB,AC va khong di qua A,B,C
a) goi ten hai nua mat phang doi nhau bo a
b) doan thang BC co cat duong thang a khong
cho doan thang a va hai diem A,B thuoc cung nua mat phang bo a va khong thuoc a
a. giai thich vi sao a khong cat doan AB
b. ve diem C khong thuoc a sao cho duong thang a cat doan thang AC. giai thich vi sao duong thang a cat doan BC
Ve 2 duong tron (A; 1cm ) va (B;2cm)cat nhau tai C va D. Duong tron tam A cat AB tai I .
a, cho biet do dai cac doan thang: AC BC AI AB?
b, I co phai la trung diem cua doan thang AB khong? Vi sao? Tinh IB?
cho duong thang d va ba diem M,N,P bat ki.
a)neu duong thang d khong cat hai doan thang MN ma ko cat doan MP thi d co cat doan NP k?tai sao?
b)neu duong thang dcat doan thang MN ma ko cat doan thang MP thi d co cat doan thang NP ko?tai sao?
giup minh di,minh dang rat can
Cho doan thang OO' =6 cm . Ve cac duong tron tam O ban kinh 4 cm va tam O' ban kinh 3 cm chung cat nhau tai A va B ; cat doan thang OO' lan luot tai M va N.
a,Tinh AO , BO , AO' , BO' ?
b, Nco phai la trung diem cua doan thang OO' khong ? Vi sao ?
c,Tinh MN ?