So we're doing proofs in class and I was wondering:
Normally in two-column proofs you need Statements and Reasons, where Reasons are normally postulates, definitions, other theorems, or givens.
What category does CPCTC (Corresponding Parts of Congruent Triangles are Congruent) fit into? If it is a theorem, is there a proof for it?
Congruent has been defined as an equivalence relation; a relation that fulfills Reflexivity, Symmetry, and Transitivity.