Answer:
That would be the side-side-side (SSS) postulate, which states that if all the sides of a triangle are in a fixed ratio to all the corresponding sides of another triangle, then the two triangles are said to be congruent.
Step-by-step explanation:
Looking at triangles ABC and DEF, we notice that:
[tex]\frac{AB}{DE} = \frac{AC}{DF}=\frac{BC}{EF}[/tex]
since
[tex]\frac{3}{18} = \frac{6}{36}=\frac{7}{42}=\frac{1}{6}[/tex]
Let me know if you have further questions.
