The magnitude of vector \[\overrightarrow{A},\,\overrightarrow{B}\] and \[\overrightarrow{C}\] are respectively 12, 5 and 13 units and \[\overrightarrow{A}+\overrightarrow{B}=\overrightarrow{C}\] then the angle between \[\overrightarrow{A}\] and \[\overrightarrow{B}\] is [CPMT 1997]

• A.    0
• B.    \[\pi \]
• C.    \[\pi /2\]
• D.    \[\pi /4\]