4. (7 points) On the plane, there is a square $A B C D$ with side length 1 and a point $X$ (see the figure). It is known that $X A=\sqrt{5}, X C=\sqrt{7}$. What is $X B$?

![](https://cdn.mathpix.com/cropped/2024_05_06_e4cc57f832254e24a588g-2.jpg?height=428&width=502&top_left_y=294&top_left_x=777)