The problem is asking for a proof of congruence between triangles $\triangle DEF$ and $\triangle HGF$, with given information:

• $\overline{EF} \cong \overline{GF}$ (EF and GF are congruent)
• $\angle EDF \cong \angle GHF$ (Angle EDF and angle GHF are congruent)

To begin a formal proof, we would typically use a two-column proof with "Statements" and "Reasons." Here's how you can structure the steps:

Proof Outline:

1. Statement 1: $\overline{EF} \cong \overline{GF}$
   • Reason: Given
2. Statement 2: $\angle EDF \cong \angle GHF$
   • Reason: Given
3. Statement 3: $\overline{DF} \cong \overline{HF}$
   • Reason: Reflexive property (since both triangles share side $DF = HF$)
4. Statement 4: $\triangle DEF \cong \triangle HGF$
   • Reason: SAS (Side-Angle-Side) Congruence Postulate (because two sides and the included angle are congruent)

Explanation:

1. The given information tells us that side $EF$ is congruent to side $GF$, and angle $EDF$ is congruent to angle $GHF$.
2. Since side $DF$ is common to both triangles, this leads to the use of the SAS postulate.
3. The SAS postulate states that if two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, the triangles are congruent.

Would you like more details or have any questions?

Here are five follow-up questions you can consider:

1. How do you determine which congruence postulate or theorem to use in a proof?
2. What is the significance of the reflexive property in proving congruence?
3. Can two triangles be congruent if only two sides are known to be congruent?
4. What other methods can be used to prove triangle congruence (besides SAS)?
5. Why is the order of vertices important when writing triangle congruence?

Tip: Always check if the corresponding parts of triangles are properly aligned in proofs to avoid mistakes in congruence statements.