a, Tren mat phang toa do ve tam giac ABC co A(1;2)   ;         B(1;-3)          C(4;-3)

b, Tinh chu vi tam giac ABC

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Bai 1;

Ve tren mat phang toa do Oxy cac diem A;B va C.Tinh dien tich cua tam giac ABC biet :

+Diem A co toa do A(x0;y0) ma x0 +1 =0 va y0-2=0

+diem B co toa do B(x1;y1) ma (x1-2)^2+(y1+3)^2=0

+Diem C co toa do C(x2;y2) ma /x2-4/+can y2-3=0

tren mat phang toa do oxy,cho tam giac oab co A(0;4),B(3;0),dien tich tam giac oab la?

trong mat phang toa do ve tam giac ABC voi cac dinh A(3;5);B(3;-1);C(-5;-1). tam giac ABC la tam giac gi ?

ho tam giac abc . Tren nua mat phang co bo la duong thang AC chua diem B ve tia AD//BC .Tren nua mat phang doi voi nua tren ve tia AE//BC.Tren nua mat phang doi voi nua tren ve tia AE//BC a cmr 3 diem A,D,E thang hang ,b Tinh tong cac goc trong cua tam giac?

Cho tam giac ABC .goc A {90* . tren nua mat phang bo AB ko chua diem C, ve Ax vuomg goc voi AB, tren do lay D sao choAD=AB .tren nua mat phang bo AC, ko chua diem B ,ve Ay tren do lay E sao cho AE=AC a cmr BE=CD b duong thang AC va ED co vuong goc voi nhau ko?

a)xac dinh cac diem A(0;3),B thuoc 0;3);C(5;0) tren mat phang toa do

b)tinh dien tich tam giac ABC

tren mat phang toa do lay 2 diem A(1,3) ; B ( 2,4 ) . tinh do dai cua tam giac OAB

cho tam giac ABC can tai A va goc A bang 30 do .Tren nua mat phang bo AB co chua diem C ve tia Bx vuong goc BA. Tren tia Bx lay diem N sao cho BN=BA .Tinh goc BCN