tren tia Ax lay hai diem B va C sao cho AB=2cm,AC=8cm
a/ tinh do dai doan thang BC
b/ goi M la trung diem cua doan thang BC tinh do dai BM
c/ ve tia Ay la tia doi cua tia Ax tren tia Ay lay diem D sao cho AD=2cm
chung to rang diem A la trung diem cua doan thang BD
giup minh ve hinh cho minh nhanh len minh dang gap ve ca hinh cho to nua nhanh to like