Cho tam giac ABC co AB=12cm . Duong phan giac goc A cat BC tai D, biet BD=9cm . tren canh AC lay diem E sao cho CE=12,5 cm a)Tinh do dai cac doan thang DC,BC b)Chung minh DE song song voi AB; tinh do dai doan thang DE
ho tam giac ABC co AC>AB. Tren canh AC lay diem D sao cho CD=AB. Duong trung truc cau BD cat duong trung truc cua doan AC tai ). CMR OA la phan giac goc BAC
cho tam giac abc vuong tai a,co ab=9,bc=15
a) tinh do dai canh ac va so ssanh cac goc cua tam giac abc
b) tren tia doi cua tia ab lay diem d sao cho a la trung diem cua doan thang bd.chung minh tam giac bcd can
c) goi k la trung diem cua canh bc. duong thang dk cat canh ac tai m.tinh do dai doan thang mc
d) duong trung truc cua canh ac cat duong thang dc tai q.chung minh ba diemb,m.q thẳng hàng
Cho tam giac ABC vuong tai A, canh AB=6, AC=8. Duong phan giac cua goc ABC cat canh AC tai D. Tu C ke CE vuong goc voi BD tai e.
Goi EH la duong ca cua tam giac EBC. CM CH.CB=ED.EB
Cho tam giac ABC vuong tai A (AB<AC), duong cao AH. Tren canh AC lay diem E sao cho AE=AB. Goi M la trung diem cua BE. Chung minh rang HM la tia phan giac cua goc AHC
C tam giac ABC can tai A tren tia doi CA lay diem E sao cho CE=AC tia phan giac góc A cat be tai D biet dien tich tam giac BDC= 10 tinh dien tich tam giac ABE.
Cho tam giac ABC deu co canh dai 12cm, goi M la trung diem cua BC, lay diem D tren canh AB, diem E tren canh AC sao cho AD = 3cm, AE = 8cm
a) chung minh tam giac MBD dong dang voi tam giac ECM
b) tinh goc DME va ty so ME/MD
c) chung minh tam giac MBD dong dang voi tam giac EMD
d) chung minh DM la tia phan giac cua goc BDE
cho tam giac vuong can abc . Tren canh AB lay diem M sao cho BM=2MA tren nua mat phat phang bo ab khong chua diem C ve duong thang Bx vuong goc voi AB , tren Bx lay diem N sao cho BN=1/2AB.Duong thang MC cat NA tai E, duong thang BE cat duong thang AC o F.CMR: AF=AM
cho tam giac ABC co AB=6,AC=8,BC=10.ve duong cao AD cua tam giac ABC
A/ cm:tam giac ABC vuong tai A va tam giac ABD dong dang tam giac CAD
B) tren AB lay F sao cho AB =3EF .tu D ve duong thang vuong goc voi FD,duong thang nay cat AC tai E.cm: goc AFD =goc CED
C) tinh ti so CE/CA