It's actually
.
Clearly is a solution.
Try graphing the equation .
Clearly it has one root at about , but I don't believe there's a way to solve it exactly (I may be wrong).
You might want to use a Heuristic method like the Bisection Method or Newton's Method to increase the accuracy.
Edit: And as Mr F says, it doesn't lie in the domain anyway... this post is for future reference :P