1) Congruent parts possess the same length, or measure (if angles).
2) As we can see, by the marks on the angles notation within each triangle we can state the following:
[tex]\begin{gathered} AB\cong ED \\ AC\cong DF \\ BC\cong EF \end{gathered}[/tex]Note that was possible since we could base ourselves on the measure of those angles.
3) Thus, we can state that these triangles as we can see, fall under the case of:
SSS - Side Side Side Congruence
Given that those three sides are congruent to each other.