Answer:
XF·XG = 17
Step-by-step explanation:
Drawing a cyclic quadrilateral from side lengths is interesting enough. I have no idea how to compute the desired value, but my geometry program says it is 17.
In the attached, XF is line segment m, approximately 7.63 in length. XG is line segment n, approximately 2.23 in length. The product is the number "o", shown at the end of the red arrow.