Answer
$\triangle$CFE ≅ $\triangle$DEF by Side-Side-Side (SSS) congruence Postulate
Work Step by Step
If you separate △CFE and △ DEF the first thing to notice is FE ≅ EF by the reflexive property of congruence, then you can use the given of CF ≅ DE and CE ≅ DF, then using the SSS Congruence postulate, △ CFE ≅ △DEF.
