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.
Explanation:
Looking at triangles ABC and DEF, we notice that:
![(AB)/(DE) = (AC)/(DF)=(BC)/(EF)](https://img.qammunity.org/2021/formulas/mathematics/high-school/rty1ako7unkvq6blfl8o6ms2jv8eg9yen2.png)
since
![(3)/(18) = (6)/(36)=(7)/(42)=(1)/(6)](https://img.qammunity.org/2021/formulas/mathematics/high-school/fci7bn0e49efb57qj9digcoxk6mj7egm4c.png)
Let me know if you have further questions.