Chung to rang neu hai duong thang song song thi cac tia phan giac cua moi cap goc dong vi song song 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

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 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 hay chung to rang goc BAE=goc BEA

CO AI GIAI NHANH HO MINH VOI

17)cho tam giac can ABC , goc A=120 do , phan giac AD.Tu B ke duong thang song song voi AD cat tia CA o E

a)chung minh tam giac ABE la tam giac deu

b)so sanh cac canh cua tam giac BEC

1)So vo duoc thuong cua 3 lop 7A ;7B ; 7C lan luot ti le voi 2;3;4 .Tinh so vo moi lop biet rang so vo cua lop 7A va 7c nhieu hon so vo cua lop 7B la 36 quyen

2) cho tam giac co goc abc = 60do;goc ACB=50do.Goi AD la tia phan giac goc BAC[D thuoc BC]

a)Tinh goc BAC;goc ADc

b)Qua B ke duong thang d song song voi AD ,d cat duopng thang AC tai M.Chung minh goc MBA = goc BMA

c)Goi Ax la tia phan giac cua goc BAM.Chung minh Ax vuong goc voi BM

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