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

Tren duong thang xy lay 2 diem A va B sao cho AB = 5 cm . Lay diem C thuoc doan thang xy sao cho AC = 2 cm . Tinh BC.

cho doan thang ab dai 6cm tren tia ab lay diem c sao cho ac=4cm a chung to rang diem c nam giua a va b b tinh do dai doan thang cb c lay diem d thuoc duong thang ab sao cho bd=3cm tinh do dai doan thang cd

cho diem O thuoc duong thang xy. tren tia Ox lay diem A sao cho OA 3cm, tren tia Oy lay diem B,C sao cho OB = 9cm, OC = 1cm.

a) tinh do dai doan thang AB,BC

b) goi M la trung diem cua doan thang BC. tinh CM ; OM

Tren duong thang x,y lay o.Lay diem a thuoc tia ox,B thuoc tia oy sao cho OA=2cm;OB=2oa

A)Tinh do dai doan AB?

B)Goi Yla trung diem cua OB.Chung minh O la trung diem cua doan thang AI

C) Tren duong thang xy lay 100 diem diem phan biet(khac O,A,B,I).Noi 2 diem ta duoc mot doan thang.Hoi co bao nhieu duong thang tao thanh?

giup minh voi! HELP ME!!!!!

Tim x,y biet

a.7x5y31/3va x-y=2

b.4x7+1y5  chia het cho 9

cau 1 :ve doan thang ab = 20cm va diem C thuoc AB sao cho AC = 3/8AB.Tinh do dai cac doan AC.Lay M thuoc AB sao cho C la trung diem cua doan thang BM.Chung minh diem M ka trung diem cua doan thang AB

(mik dang can gap)

tren duong thang a lay 2 diem A va B sao cho AB=2cm lay diem C sao cho A la trung diem cua doan thang BC lay diem D sao cho B la trung diem cua doan thang AD a)tinh do dai doan thang CD   b) goi trung diem cua AB la M tim trung diem cua doan thang CD

cho duong thang d va doan thang ab nam ngoai duong thang d , ve diem a' doi xung voi diem a qua d va diem b' doi xung voi siem b qua d , lay bdiem c thuoc doan thang ab , ve diem c' doi xung voi c qua d . chung minh ab=ab'