I have a problem and final answer that I got from a journal. I was trying to solve it but never reach the final answer. Here is the problem. I have tried up to this so far
The last integral I tried to solve with mathematica and it gives very different result that is very far from the actual one
$-\frac{\csc (\beta ) \csc (\theta ) \sqrt{\cos (2 \beta )+\cos (2 \theta )} \tanh ^{-1}\left(\frac{\sec (\beta ) \sqrt{\cos (2 \beta )+\cos (2 \theta )}}{\sqrt{2}}\right)}{\sqrt{2-2 \cot ^2(\beta ) \cot ^2(\theta )}}$
I am not sure where, I am doing mistake. Shall I go for any other method?