To determine the scale factor used in a dilation of a triangle (or any geometric figure), you need the lengths of corresponding sides of the two triangles: the original triangle (triangle D) and the dilated triangle (triangle D').
The scale factor \( k \) can be found using the formula:
\[ k = \frac{\text{Length of a side of triangle D'}}{\text{Length of the corresponding side of triangle D}} \]
If you have the lengths of at least one side from triangle D and the corresponding side from triangle D', you can plug those values into the formula to calculate the scale factor.
If you provide the lengths of the sides, I can help you calculate the scale factor.