The value of \({\tan ^{ - 1}}\left( {\frac{1}{7}} \right) + {\tan ^{ - 1}}\left( {\frac{1}{{13}}} \right)\) is
1
\({\tan ^{ - 1}}\left( {\frac{2}{7}} \right)\)
2
\({\tan ^{ - 1}}\left( {\frac{2}{{13}}} \right)\)
3
\({\tan ^{ - 1}}\left( {\frac{2}{9}} \right)\)
4
\({\tan ^{ - 1}}\left( {\frac{1}{9}} \right)\)