Cho 1 duong thang cat 2 duong thang song song,Hay chung minh rang:

a,Cac tia phan giac cua 1 cap goc so le (hoac so le ngoai thi song song voi nhau

b,Cac tia phan giac cua 1 cap goc dong vi thi song song voi nhau.

c,Cac tia phan giac cua 1 cap goc trong cung phia(hoac ngoai cung phia) thi vuong goc voi nhau.

CMR : neu 1 dg thang cat 2 dg thang song song thi 2 tia phan giac cua 1 cap goc dong vi song song voi nhau

tam giac ABC co tia phan giac cua goc B cat AC o D qua A ke duong thang song song voi BD duong thang nay cat duong thang BC o E hay chung to rang goc BAE=goc BEA

CO AI GIAI NHANH HO MINH VOI

cho 2 duong thang song song a và b và 1 cat tuyên c .hai tia phan giac cua 1 cap goc trong cung phai cat nhau tai i .chung minh rang i cach đều 3 dg thang a,b,c

Cho biet tu diem A thuoc tia phan giac cua goc xoy co mu nha! ve duong thang song song voi Ox cat Oy tai B va ve duong thang song song voi Oy tai C a)chung minh BOA=AOC ,b) chung minh AO la tia phan giac cua BAC

tam giac ABC co tia phan giac cua goc B cat AC o D.Qua A ke duong thang song song voi BD,duong thang nay cat duong thang BC o E.Chung minh rang goc BEA = goc BAE

a) duong thang c co vuong goc voi duong thang b ko vi sao

b)cho doan thang d cat 2 duong thang a va b tai A va B cho niet goc A1= 115do . Tinh so do cac goc B2,B3,A3

c)goi AX va By lan luot la tia phan giac cua cac goc A1 va B CHUNG MINH Ax song song By

Cho \(\Delta ABC\)can tai A. Tu B ke duong vuong goc AB, tu C ke duong vuong goc voi AC.Hai duong thang cat nhau tai D. Chung minh rang

a, AD la phan giac cua goc BAC

b, Tren tia doi cua tia BD lay diem E, tren tia doi  cua tia CD lay diem F sao cho CF= BE. chung minh AE= AF

c, Chung minh EF song song voi BC

cho tam giac abc phan gic goc b cat ac o d. qua d ke duong thang cat ab o e sao cho edb =ebd qua e ke duong thang song song voi bd cat ac o f chung minh ed song song voi dc; ef la tia phan giac cua aeb