Find the summation of this series :
$\displaystyle \sum_{k=1}^{\infty} \tan^{-1}[ \frac{ y^2 }{ k^2 + x^2 } ]$
Consider $\displaystyle sinx = x \prod_{j=1}^{\infty} [ 1 - \frac{x^2}{(j \pi)^2}]$
Find the summation of this series :
$\displaystyle \sum_{k=1}^{\infty} \tan^{-1}[ \frac{ y^2 }{ k^2 + x^2 } ]$
Consider $\displaystyle sinx = x \prod_{j=1}^{\infty} [ 1 - \frac{x^2}{(j \pi)^2}]$