To determine the scale factor used in the dilation of line segment \( AB \) with a center point of dilation at the origin, we start by identifying the coordinates of points \( A \) and \( B \) and their corresponding dilated points \( A' \) and \( B' \).
- Point \( A \) is at \( (9, 9) \) and dilates to point \( A' \) at \( (3, 3) \).
- Point \( B \) is at \( (6, 6) \) and dilates to point \( B' \) at \( (2, 2) \).
The formula for the scale factor \( k \) in a dilation centered at the origin is given by the ratio of the distance of the points after dilation to the distance of the original points:
\[ k = \frac{x'}{x} = \frac{y'}{y} \]
For point \( A \):
\[ k = \frac{3}{9} = \frac{1}{3} \]
For point \( B \):
\[ k = \frac{2}{6} = \frac{1}{3} \]
In both cases, the scale factor is the same. Therefore, the scale factor used in the dilation of line segment \( AB \) is:
\[ \frac{1}{3} \]
Thus, the answer is:
Start Fraction 1 over 3 End Fraction