The missing statement is that ∠HGF ≅ ∠IGF, and the reason for this is that corresponding parts of congruent triangles are congruent.
The missing statement in the proof is:
5. ∠HGF ≅ ∠IGF
The reason for this statement is Corresponding Parts of Congruent Triangles are Congruent (CPCTC).
Here's why:
We are given that ΔABH ≅ ΔEDI (Step 1).
We are also given that ∠GH ≅ ∠GI (Step 2).
Since the triangles are congruent, their corresponding angles are congruent (CPCTC). Therefore, ∠HAB ≅ ∠IED (Step 3).
In Step 4, we are given that ∠A ≅ ∠E.
Combining Steps 3 and 4, we have ∠HAB + ∠A ≅ ∠IED + ∠E.
Simplifying the expression, we get ∠HAG ≅ ∠IFG.
Therefore, based on CPCTC, we can conclude that ∠HGF ≅ ∠IGF (Step 5).