Cho tam giac ABC ( AB<AC). Tren canh AB lay diem E sao cho AE=AD . Tia phan giac cua goc a cat canh BC tai D . Chung minh : a,tam giac ABD=tam giac AED b,DE=DB c, BE vuong goc voi AD
1.cho tam giac ABC. tren tia doi cua tia BA lay diem D sao cho BD=BA. tren canh BC lay diem E sao cho BE =1/3 BC. goi K la giao diem cua AE va CD. chung minh rang DK=KC
2. cho tam giac ABC can tai A co AB =AC =5cm, BC=3cm. ke trung tuyen AM
a) chung minh AM vuong goc BC
b) tinh do dai AM
1. cho tam giac ABC. tren tia doi cua tia BA lay diem D sao cho BD=BA. tren canh BC lay diem E sao cho BE=\(\dfrac{1}{3}\)BC. goi K la giao diem cua AE va CD. Chung minh rang DK=KC
2. cho tam giac ABC can tai A co AB=AC=5cm,BC=3cm. ke trung tuyen AM
a. Chung minh rang AM vuong goc BC
b. tinh do dai AM
tren canh Ax cua goc nhon xay lay 2 diem B va D sao cho B nam giua A va D tren Ay lay C va E sao cho AB=AC va AD=AEa) chung minh tam giac ACD = tam giac ABE b) goi I la giao diem cua CD va BE so sanh goc IBD = goc ICE
Cho tam giac deu ABC. Tren canh AB lay diem D sao cho AD=1/3 AB. Tu D ke duong thang vuong goc AB cat A o E, qua E ke duong thang vuong goc AC cat BC o F. Chung minh. a, DF vuong goc BC. b, Tam giac DEF la tam giac deu
cho tam ABC can tai dinh A, trung truc cua canh AC cat CB tai D(D nam ngoai doan BC).Tren tia doi AD lay E sao cho AE=BD.Chung minh tam giac DCE can(goi y can chung minhCD=CE)
Cho tam giac ABC vuong tai A, goc C=30do. Duong cao AH. Tren canh HC lay diem D sao cho HD=HB. Tu C keo CE vuong goc AD. Cm. a, Tam giac ABD deu. b, EH song song AC
Cho tam giac ABC biet AB nho hon AC.Tren tia BA lay diem D sao cho BC bang BD. Noi C voi D. Phan giac goc B cat canh AC ,DC tai E, I. Chung minh tam giac BEC bang tam giac BID .Tu A ve duong vuong goc voi DC , H thuoc DC.Chung minh AH song song voi BI
Cho tam giac abc can tai a, a=30 do. Tren nua mat phang bo ab chua diem c ve tia bxvuong goc ba. Tren tia bx lay diem n sao cho bn=ba. Tinh so do goc bcn
