cho tam giac ABC.qua A ve xy song song voi BC.Tu M tren canh BC, ve cac duong thang song song voi AB,AC.chung cat xy theo thu tu la D,E.CMR:3 duong thang AM,BD,CE cung di qua 1 diem
ai giai dc minh tick cho
cho tam giac abc vuong tai a. tren canh ab lay d, tren canh ac lay e sao cho ad=ae, cac duong thang vuong goc ve tu a va e voi cd cat bc tai g va h. duong thang eh va duong thang ab cat nhau o m. duong thang ve tu a songsong voi bc cat hm tai i. cmr: tam giac acd bang tam giac ame
cho tam giac abc vuong can o A tren AB lay D tren AC lay E sao cho ad=ae cac dt vuong goc ke tu diem A va E
toi CD cat BC o G va H va duong thang AB cat nhau o M duong thang ve tu A va song song BC cat MH o I CMR Tam giac ACD =tam giac AME
cho tam giac abc tren canh bc lay diem d va e sao cho bd = ce qua d va e ke cac duong thang song song vs ab theo thu tu tai i va k cm di +ek=ab
cho tam giac ABC can tai A co A < 90 do, duong vuong goc voi AB tai B va duong thang vuong goc voi AC tai C va chung cat nhau tai M.
a, c/m tgABM = tgACM, AM la phan giac cua goc BAC
b, Qua M ve duong thang song song voi AC, duong thang nay cat AB o D. Tren tia doi cua tia CA lay diem E sao cho CE = DB, c/m tgDBM = tgECM
c, BC cat DM tai F. c/m DF = CE
cho tam giac abc co cac cach khong doi. lay diem d va m tren canh ab sao cho ad = bm. qua d va m ve cac duong thang song song voi bc cat ac lan luot tai e va n. chung minh de+mn khong doi khi d va m di chuyen tren canh ab.
bai 1. cho doan thang zz' cat 2 duong thang song song xx' va yy' thu tu tai A vaB . ve tia At la tia phan giac cua xAz' va tia BM la tia phan giac cua zBy'. CMR : At // BM
bai 2 cho tam giac ABC tren nua mat phang bo BC chua diem A ve tia Cx song song voi AB. Ve tia Cy la tia phan giac cua ACx. ve tia Az la tia phan giac cua BAC. CMR Cy // Az
Cho tam giac ABC co goc A = 60 do . Cac duong phan giac BD va CE cat nhau tai I . Tren canh BC lay M sao cho BM = BE . a) Chung minh tam giac MID can
b) ve duong thang vuong goc voi BI tai B va vuong goc voi CI tai C , chung cat nhau o K . CMR : 3 diem A,I,K thang hang
cho tam giac ABC vuong tai A ve phan giac cua goc ABC tia nay cat canh AC tai K tren canh BC lay diem D sao cho BD= BA a)chung minh KA=KD b)duong thang AB cat duong thang DK tai E chung minh tam giac KDC c) chung minh tam giac BEC can tai c