Phat bieu Ve hinh va ghi gia thietb,ket luan ki hieu tinh chat 2 dg thang song song

Phat bieu ve hinh va ghi gia thiet, ket luan duoi dangki hieu dau hieu nhan biet 2dg thang sog song

Nhanh nhe cac ban

ve hinh va ghi gia thuyet, ket luan các dinh li sau : a) neu 1 duong thang cat 1 trong 2 duong thang song song no cat duong thang kia

ve hinh va ghi gia thiet va ket luan cho dinh ly sau

tia phan giac cua goc thi tao voi 2 canh cua 2 goc bang nhau

Cho tam giac ABCDvuong tai a .Goi P,E,F lan luot la trung diem AB,BC,AC

a, viet gia thiet va ket luan va ve hinh

b,tu giac ADEF la hinh gi ? vi sao ?

c, tu D ke duong thang //voi BEcat EF tai I chung minh BF vuong goc voi D la hinh binh hanh

d, tim dieu kien de tu giac AECI la hinh vuong

phat bieu tien de o clit ve duong thang song song

Cau 1: neu ket luan ve cuong do dong dien va hieu dien the cua doan mach trong doan mach mac noi tiep va doan mach mac song song

Cau 2 :neu cac bien phap an toan dien ma em biet

Phat bieu nao sau day la dung:

A) Hai duong thang cung song song voi mot duong thang thi chung song song voi nhau

B) Chi co mot duong thang song song voi duong thang da cho

C) Chi co mot duong thang di qua mot diem song song voi duong thang da cho

D) Tat ca cac phat bieu tren deu sai

tren mot duong thang song song lay n diem a1,a2,a3,....an .qua cac diem nay ve cac duong thang song song voi nhau .tinh gia tri cua n de trong hinh co dung 100 tia

Cho tam giac ABC .Qua dinh A ve duong thang a song song voi BC ,qua dinh B ve duong thang B song song voi AC .

Ve hinh va neu cach ve