atan(1i*[1 - x^2i]/[1 + x^2i]) = a assume, -pi/2 < a <= pi/2 , solve, x ?

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   Hello Everyone.

   The question : atan(1i*[1 - x^2i]/[1 + x^2i]) = a  assume, -pi/2 < a <= pi/2 , solve, x ?

         Thanks in advance.

                Regards.

[-MFra- · Accepted solution]