Answer:
1
Step-by-step explanation:
A dilation of .1 or 1/2 would decrease the size. Since the numbers are smaller than zero the triangles would no longer be congruent. A dilation of 10 would increase the size of the triangle, causing the triangles to no longer be congruent. A scale fact of one is equivalent to the same size because 1 does not increase or decrease the size.
