To determine the scale factor used in the dilation of line segment AB with a center point of dilation at the origin, we can compare the lengths of the original line segment AB and the dilated line segment A' B'.
The original line segment AB has a length of 3 units (distance from point A to point B).
The dilated line segment A' B' has a length of 1 unit (distance from point A' to point B').
To find the scale factor, we divide the length of the dilated line segment by the length of the original line segment:
1 / 3 = 1/3
Therefore, the scale factor used in the dilation of line segment AB with a center point of dilation at the origin is 1/3.