dien vao cho trong cho cac phat bieu sau:
a)hinh tao thanh boi diem O va 1 phan duong thang bi chia ra boi diem Oduoc goi la 1 .......................
b)diem R bat ki nam tren duong thang xy la goc chung cua.............................
c)neu diem A nam giua 2 diem B va C thi:
-hai tia............................doi nhau
-hai tia CA va ..........................................trung nhau
-hai tia BAva BC ...............................