cho do dai doan thang AB dai 8 cm. Hay ve doan thang CD bang do dai cua doan thang AB giam 2 lan ?

( Hay tra lop day du nhe )

tren doan thang AC co do dai 12 cm ,lay diem B sao cho AB=5 cm .a, tinh do dai cua doan thang BC.b,goi M,N lan luot la trung diem cua doan thang AB ,BC . tinh do dai doan thang MN.c, lay diem D thuoc tia doi cua tia CA sao cho CD =7 cm . chung to rang diem C la trung diem cua doan thang BD

doan thang ab dai 6 cm .M la trung diem cua doan thang ab N la trung diem cua doan thang AM Tinh do dai doan thang NB

Do dai doan thang ANla

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.

Doi doan thang ab dai 6 xang -ti  -met ;doan thang cd dai 2 xang-ti -met.Hoidoan duong ab dai gap may lan doan thang cd

cho diem B thuoc duong thang AC \((\)B khong trung voi A va C\()\).Hai diem D,E lan luot la trung diem cua doan thang AB,AC.Chung to do dai doan thang BC gap doi do dai doan thang DE

biet 2/3 do dai doan ab la 20 m . va do dai doan thang ab baang 4/5 do dai doan thang cd . doan thang cd dai

Duong gap khuc ABCD co AB bang 18 cm BC bang 20 cm doan thang CD ngan hon doan thang BC tinh do dai duong gap khuc ABCD

doan thang AB dai 125 cm . M vaN lan luoc la diem chung cua AB va CB . tinh do dai doan thang AD ?