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 goc vuong xoy diem a thuoc tia ox diem b thuôc tia oy . dduong trung cua doan thang oa va oc cat nhau o d duong trung truc cua doan thang . ob cat oy o e . goi c la giao diem cua hai duong trung truc do c/minh :
a) ce=od
b) ce vuong goc voi cd
c) ca=cb
d)ca//de
cho doan thang AB co O la trung diem .Ve Ax va By vuong goc voi AB tai Ava B .Lay C tren Ax , duong thang vuong goc voi OC cat By tai D.CMR DC=AC+BD.??????????????????????
BAN NAO GIUP MINH NHANH NHAT MINH TICH CHO<3
cho o trung diem doan thang ab. tren cung mot nua mat phang bo ab ve cac tia ax, by cung vuong goc voi ab. lay c bat ki tren ax roi ve duong thang vuong goc voi octai o cat by o d. chung minh a, oc la phan giac goc acd . b, ca= ac + BD
Cho tam giác ABC vuông tại A.Ve AD vuong voi bc.tren doan thang ah lay diem d.tren tia doi cua HA lay diem E sao choHE=AD .duong thang vuong goc voi AH tai D cat AC o F.CMR:<BEF=90°
(Viết ca loi giai va ve hinh nhe)
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?
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 doan thang AB , diem O nam giua A va B . Ke tia Ox vuong goc voi AB . tren tia OX lay cac diem C,D sao cho OC = OA , OD =OB . Goi M la trung diem cua AD , N la trung diem cua BC . Chung minh rang :
a. AD = DC
b. ON = OM , OM vuong goc voi ON .
Cho doan thang AB, co O nam giua A,B. Ke Ox vuong goc AB. Tren Ox lay C,D sao cho OC=OA, OD=OB. Goi M la trung diem cua AD , N La trung diem cua BC. CMR AD=CB
OM vuong goc voi ON
cho tam giac ABC co AB =6 ,AC=8, BC=10. 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 chung minh rang : tam giac ABC vuong tai A
