Question
Let ${\tan ^{ - 1}}y = {\tan ^{ - 1}}x + {\tan ^{ - 1}}\left( {{{2x} \over {1 - {x^2}}}} \right),$
where $\left| x \right| < {1 \over {\sqrt 3 }}.$ Then a value of $y$ is :
where $\left| x \right| < {1 \over {\sqrt 3 }}.$ Then a value of $y$ is :