Answer:
[tex] \angle A \cong \angle D [/tex]
Step-by-step explanation:
The Side-Angle-Side method cana only be used when information given shows that an included angle which is between two sides of a ∆, as well as the two sides of the ∆ are congruent to the included side and two sides of the other ∆.
Thus, since John already knows that [tex] \overline{AB} \cong \overline{DE} [/tex] and [tex] \overline{AC} \cong \overline{DF} [/tex], therefore, an additional information showing that the angle between [tex] \overline{AB} [/tex] and [tex] \overline{DE} [/tex] in ∆ABC is congruent to the angle between [tex] \overline{AC} [/tex] and [tex] \overline{DF} [/tex] in ∆DEF.
For John to prove that ∆ABC is congruent to ∆DEF using the Side-Angle-Side method, the additional information needed would be [tex] \angle A \cong \angle D [/tex].
See attachment for the diagram that has been drawn with the necessary information needed for John to prove that ∆ABC is congruent to ∆DEF.
