To find the length of the line \( x \) using the geometric mean theorem, we can apply the formula where the length of the segment \( x \) from the vertex to the hypotenuse is given by:
\[ x = \sqrt{a \cdot b} \]
where \( a \) and \( b \) are the segments of the hypotenuse created by the line \( x \). In this case, the hypotenuse is divided into segments of lengths 5 and 12.
Thus,
\[ x = \sqrt{5 \cdot 12} \]
Calculating this gives:
\[ x = \sqrt{60} \]
Now, simplifying \( \sqrt{60} \):
\[ \sqrt{60} = \sqrt{4 \cdot 15} = 2\sqrt{15} \approx 2 \cdot 3.872 = 7.744 \]
Rounding this value gives approximately \( 7.75 \).
So, the correct answer is:
7.75