The tangent lines are perpendicular to the diameter. Hence, we have a right triangle given:
Now, we can use the Pythagorean theorem to find the missing segment length.
Therefore, we can write the next equation:
Let set x for the missing segment length.

Solve for x:
![\begin{gathered} x^2=12^2-9.6^2 \\ x=\sqrt[]{12^2-9.6^2} \\ x=7.2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/lel4tf8o43k769od86iv1bxrfnbhj35enq.png)
Hence, the correct answer is option C.