Question

Help? WILL MEDAL!

Answer 1

Do to the fact that we prove that one side of one triangle is equal to the corresponding side of the other they are congruent. `BE corresponds with ED` `AC corresponds with EC` and `BA corresponds with CD`. We prove each are equal to each other so we solve this by SSS Theorem which proves they are congruent.

Answer 2

In short, yes. Though its best to know why.