Bai 1:Tren duong thang xy lay 3 diem A,B,C theo thu tu do.A,Viet ten 2 tia goc A,hai tia goc B,hai tia goc CB,Viet 2 tia doi nhau goc BC,Viet ten 2 tia trung nhau goc A,hai tia trung nhau goc BGiup mik voi mik vote 5diem va follow nguoi do
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