CHO DOAN THANG MN=7cm hay ve duong trung truc cua doan thang MNva neu cach ve
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)
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)
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
Ve duong thang a, tu hai dem A,B nam ngoai duong thang a , dung AC;BD vuong goc voi a (C ,D Thuoc a) Ve duong thang d la duong thang trung truc cua CD cat AB tai N
Cho doan thang AB=4cm ve duong tron tam A ban kinh 3cm va duong tron tam B ban kinh 3cm cat nhau tai C va D .chung minh CD la duong trung truc cua AB. Viet ca GT va KL nhe
Cho tam giac ABC co AB=BC . Goi I la trung diem cua AB . Tren tia CI lay D sao cho D nam khac phia voi C so bo la doan thang AB
a/ c/m tam giac ADC=BDC
b/ suy ra CD la duong thang trung truc cua AB
{ ko can ve hinh nhung viet ro gium minh cai cam on nhieu }
cho duong thang AB ve duong thang trung truc cua duong thang do
cho đoạn thẳng CD =4cm.vẽ duong thang trung truc d cua doan CD . qua C ve duong m sao cho m//d
a; ve duoc bao nhieu duong thang nhu m, vi sao?
b;CD co vuong goc voi m khong?,vi sao?