Bai 20:Ve doan thang AB dai 2cm va doan thang BC dai 3cm roi ve duong trung truc cua moi doan thang ay (Ve hinh trong hai truong truong hop:ba diem A,B,C khong thang hang,ba diem A,B,C thang hang)

a/cho doan thang AB dai 6cm

Hay ve duong thang a la trung truc cua AB

b/Neu cach ve

ve doan thang PQ=10cm ve duong thang trung truc cua doan thang PQ 

tren duong thang trung truc cua doan thang PQ lay diem M ko thuoc PQ .Qua diem M lay ve duong thang dsong song vo PQ

a) ve doan thang pq=10 cm . ve duong trung truc cua doan thang pq 

 tren duong trung truc cua doan thang  pq lay diem m khong thuoc pq . qua diem m ve duong thang d\\ pq

Cho 1 doan thang AB dai 4cm.Ve duong thang d la duonbg trung truc cua doan thang AB,lay O thuoc d.Qua O ve doan thang OC=2cm sao cho OC vuong goc voi d.Qua O ve doan OD=1cm sao cho OD vuong goc voi d.Chung minh C,O,D thang hang.D co phai la trung truc cua doan thang CD ko?Vi sao?(Mik can ve hinh va loi giai nhe,minh ve hinh ko chac chan,mong cac ban giup do)

cho▲abc co ab=6cm,ac=8cm,bc=10cm.goi k la trung diem cua doan thang bc duong trung truc cua doan thang bc cat ac tai m goi d la hinh chieu vuong goc cua c tren duong thang bm .cmr a)▲abc vuong tai a b)AB=DC c)3 duong thang AB,MK,CD di qua 1 diem giup minh voi mai mình phải nop cho co roi

Cho doan thang AB goi I la giao diem cua AB voi duong trung truc cua doan thang H tren duong trung truc di lay diem khac ko trung voi I chung minh HA =HB

ve duong thang xy.Tren xy lay 2 diem I,B roi lay diem C sao cho I la trung diem cua doan thang BC. Lay diem D sao cho B la trung diem cua doan thang ID.

a) Co phai CD dai gap 3 lan IB khong?Vi sao?

b) Ve trung diem M cua IB. Vi sao diem M cung la trung diem cua CD?

CHO DOAN THANG MN=7cm hay ve duong trung truc cua doan thang MNva neu cach ve