Question

Please help:

the congruence statements ∆ABC ≅ ∆DEF, ∆ABC ≅ ∆EFD and ∆ABC ≅ ∆FDE all are valid. what must be true about ∆ABC and ∆DEF​

Answer 1

The triangle must be equiangular and equilateral. We can see that A,B, and C are equal to all the angles on triangle DEF. We know this because of the order it’s written in.
For example, we know that angle B is congruent to angle E (first congruency ABC = DEF) because they’re both the second letter. Keep on doing this and you’ll find out all the angles are equal to one another.
We also know that the sides are equal because it says the triangles are congruent.