Final answer:
The scale factor required to dilate triangle ABC so that it's congruent to triangle EFD is 3.
Step-by-step explanation:
To find the scale factor required to dilate triangle ABC so that its image A'B'C' is congruent to triangle EFD, we need to determine the ratio between corresponding sides of the two triangles. The scale factor is equal to the ratio of corresponding side lengths. In this case, since triangle ABC is similar to triangle EFD, the corresponding sides are AB and EF, BC and FD, and AC and ED. To find the scale factor, we can compare the lengths of AB and EF. If AB is 3 times longer than EF, then the scale factor is 3.