Cho tam giac abc co a<90 do ve ra ngoai hai tam giac vuong can tai a abd va ace
1 cho tam giac abc can a , goc a bang 40 do lay d khac phia b so voi ac thoa man goc cad bang 60 do goc cad bang 80 do chung minh bd vuong goc voi ac
2 cho tam giac abc vuong can a . d la diem bat ki tren ab. tren nua mat phang bo ab tu c ve tia bx sao cho goc abx bang 135 do. duong thang vuong goc voi dc ve tu d cat bx o e . chung minh tam giac dec vuong can
3 cho tam giac abc can b goc abc bang 80 do , i la diem trong tam giac sao cho goc iac bang 10 do, ica bang 30 do tinh goc abi
4 cho tam giac abc can a co goc a bang 100 do , bc =a, ac =b ve phia ngoai tam giac abc ve tam giac abd can d co goc adb bang 140 do tinh ch vi tam giac adb theo a,b
ve hinh gium minh voi , xin mn day
cho tam giac abc co goc a bang 90 do. bd la phan giac cua goc b ve de vuong goc bc .goi f la giao diem cua ab va de
a, chung mijh tam giac abd = tam giac ebd va duong trung truc cua ae
b, chung minh tam giac dcf can
c, khi tam giac abc co goc b bang 60 do , c = 30 do va bc = 12 cm . tinh do dai dc
cho tam giac ABC co dung cao AH.ve ra ngoai tam giac ABC cac tam giac can ABD,ACE,goc ABD=goc ACE=90 do .qua C ve duong thang vuong goc BE cat ah tai k .chung minh AK=BC
Cho tam giac ABC, goc A < 90 do. Ve ngoai tam giac ABC cac tam giac vuong can tai A la ABD, ACE.
a, CM : BE=CD, BE vuong goc voi CD
b, Ke AH vuong goc voi BC, AH cat DE tai K. CM : DK=KE
cho tam giac ABC co goc A<90 do ve ra ngoaitam giac do hai doan thang AD vuong goc va bang AB, AE vuong goc va bang AC
a, chung minh DC vuong goc va bang BE
b, goi N la trung diem cua DE.Tren tia doi cua NA lay M sao cho NA=NM
chung minh AB=ME va tam giac ABC=tam giac EMA
c, chung minh MA vuong goc voi BC
giup mk cau c thoi cung dc mk dg can gap nha
Cho tam giac ABC co goc B, goc C< 90. ve ra phia ngoai tam giac ay cac tam giac vuong can abd va ace(goc ABD=ACE=90)
ke DI va EK vuong goc vs BC
CMR: 1, BI=CK
2,BC=DI+EK
Cho tam giac ABC vuong can tai A, D la mot diem bat ki tren canh AB. Tren nua mp bo AB co chua diem C, ve tia Bx de goc ABx=135 do. Duong thang vuong goc vs Dc ve tu D cat tia Bx tai E. Chung minh tam giac DEC can
cho tam giac ABC co goc A nhở hơn 90 do tren mat phang bo AB co chua diem B ve AE VUONG AC va AE =AC goi M la trung diem cua doan MA diem H sao cho MA =MH chung minh tam giac ABE = TAM GIAC ADC chung minh BH=CA chung minh GOC BAH = GOC ADE