Please Help me to prove this,

$\displaystyle tan^{-1}\left(\frac{tan2\theta + tanh2\phi}{tan2\theta - tanh2\phi}\right)+tan^{-1}\left(\frac{tan\theta - tanh\phi}{tan\theta + tanh\phi}\right)=tan^{-1}\left(cot\theta coth\phi \right)$

Thank You Very Much....