Answer:
it’s the first one
Step-by-step explanation:
because after determining angles are vertical, you must also say they are congruent :)
The missing reason in step 3 is that;
Vertical angles are congruent.
This is about angle theorems as used in each of the steps in the question.
Now, in step 2, we see that;
∠EDF and ∠ADC are vertical angles. This means that both angles which are opposite to each other are made by 2 intersecting lines which are A F and EC.
Now, in step 3, we see that;
∠EDF ≅ ∠ADC
The symbol ≅ means congruent.
Moreover, according to vertical angles theorem, it states that vertical angles are always congruent.
Thus, the missing reason in step 3 is that;
Vertical angles are congruent.
Read more here; brainly.com/question/23084273
