tam giác ABC AB=3, AC=5,BC=\(\sqrt{29}\)tính góc BAC?

Cho tam giac ABC. M la trung diem cua BC. AB=2cm, AC=4cm, AM=\(\sqrt{2}\)cm. Tinh goc BAC,BC, dien tich tam giac ABC

tam giác ABC ; AB=3 ;AC=5 ; BC=\(\sqrt{29}\).Tính góc BAC

cho tam giac ABC co ab=ac ke bd vuong goc vs ac; ce vuong goc vs ab [d\(\in\)ac; e\(\in\)ab]

a CM bd = ce

b Goi O la giao diemcua bd va ce.CM tam giac OBE = tam giac OCD

c CM AO la tian phan giac cua goc BAC AOvuong goc voi BC

Cho tam giac ABC  có Â tù , goc C = 30 độ, AB = 29,AC =40. vẽ AH \(\perp\)_{BC . Tính BH}

cho tam giac abc co goc bac=75do.goc abc=35do.phan giac cua goc bac cat canh bc tai d .duong thang qua a va vuong goc voi ad tai e.goi m la trung diem cua de .cmr:

a, tam giac acm la tam giac can

b,      ab<\(\frac{ad+ae}{2}\)

c,  cu vi tam giac abc bang do dai doan thang be

cho tam giac abc co goc B =45 do, AB = \(\sqrt{18}\) , Bc=7 . tinh AC

Cho tam giac ABC co goc B=80 do; goc C=40 do. Tia phan giac cua goc A cat BC o D.

a. Tinh goc BAC, goc ADC

b. Goi E la mot diem tren canh AC sao cho AE=AB. Chung minh: \(\Delta ABD=\Delta AED\)

C. Tia phan giac cua goc B cat AC tai I. Chung minh BI//DE

Cho tam giac ABC can tai A ke AH vung goc voi BC (H thuoc BC )

a, Chung minh AH la tia phan giac cua goc BAC

b, Ke HD vuong goc voi AB ( D thuoc AB) , HE vuong goc voi AC ( E thuoc AC). Chung minh tam giac HDE can

c, Neu cho AB = 29 cm , AH = 20 cm .Tinh do dai BC

d,Chung minh BC//DE

e, Neu cho goc BAC =120 do thi tam giac HDE tro thanh tam giac gi ? Vi sao