M____________________T_____________________O_________________________R_________________N
Theo bài ra ta có:
MN=10cm
O là trung điểm MN
=> MO=ON=1/2 MN=5cm
MT=2cm
=>TO=5cm-2cm=3cm
Ta có: TO+OR=TR
=> 3cm+OR=TR
RN=10cm-8cm=2cm
Vậy OR=10cm-2(2cm)-3cm=3cm
OR=3cm