Answer:
x=12
Step-by-step explanation:
What we have here is a secant and tangent. Using this theorem,
Given the segments of a secant segment and a tangent segment which share an endpoint outside of a circle,
The product lengths of the secant segment and external secant segment equals the length of the tangent segment squared.
In other words,
[tex]9(7 + 9) = {x}^{2} [/tex]
[tex]9(16) = {x}^{2} [/tex]
[tex]144 = {x}^{2} [/tex]
[tex]x = 12[/tex]
