Xét hình thang \(ABCD \) có \(AB//CD\)
=> \(\widehat{A}=\widehat{D};\widehat{B}=\widehat{C}\) (đồng vị)
mà \(\widehat{D}=\widehat{C}\) ( hình thang \(ABCD\) cân )
=> \(\widehat{A}=\widehat{B}\)
=> \(\Delta IAB\) cân tại I
Cho hinh thang can ABCD coAB//CD va AD cat BC tai I, O la giao diem cua AC va BD; M la trung diem cua AB. c.m M, O, I thang hang
Cho tam giac ABC co 3 goc nhon. Goi O la trung diem cua BC. Goi D la diem doi xung cua A qua BC ; E la diem doi xung cua A qua O. Chung minh rang BCDE la hinh thang can.
cho hinh vuong ABCD voi A=B = 90° AD=2BC a,ke CK vuong goc voi AD tai K.tu giac ABCK la hinh gi vi sao.b,goi AH la duong cao cua tam giacABD.Eva Flan luot la trung diem cua AH va DH.chung minh rang tu giac BCFE la hinh binh hanh.c,chung minh BE vuong goc voi À
Cho hinh thang can ABCD co AB la day nho :
a) CM: \(\Delta ADC\)=\(\Delta BCD\)
b) Goi O,Elan luot la giao dien cua ABva BD,ADva BC
Goi I,J lan luot la trung diem cua AB va DC
CM: O,E,I,J thang hang
c)CM: HD=\(\dfrac{AB+CD}{2}\) ; HC=\(\dfrac{CD-AB}{2}\) biet rang BH\(\perp\)CD va H thuoc DC
Cho hinh thang can ABCD co AB//CD , BD la phan giac goc D va DB vuong goc voi BC . Biet AB =4 .Tinh chu vi hinh thang
co hinh thang can ABCD(AB//CD) co AD=AB goc D=60
tinh cac goc cua hinh thang
C/M DB la phan giac cua goc ADC
BCD la tam giac can vi sao ?
Cho tam giac ABC nhon co AB > AC co duong cao AH. Goi M, P, Q la trung diem cua AB, CA va BC. CMR :
a, PQ la trung truc cua AH
b, MPQH la hinh thang can
Cho hinh thang can ABCD AB//CD góc C =60°. DB la phan giac cua goc B. Duong cao BH. AB=4. Tinh chu vi hinh thang. Tinh duong cheo BD va duong cao BH.
cho hinh thang can ABCD day be AB = canh ben BC , duong cheo AC vuong goc voi canh ben AD
a) Tinh cac goc cua hinh thang
b) chung minh day lon bang 2 lan day nho
nho cac ban giup do mk moi lap nick
XIN CAM ON A
P/s : may tinh ko danh dc daus ahihi
cho hinh thang can ABCD , goc ACD = 60 do . AC giao BD tai O . E,F,G lan luot la trung diem cua OA.OD,BC . Tam giac EFG la tam giac gi ? Vi sao ?
