Question

With what should a proof always begin?

Answer 1

It should start with the rule you are to prove, followed by what you are given, followed by any constructions you need to make, followed by your proof.

Answer 2

The given information.

Answer 3

an axiom, or assumption which we use to derive other statements

Answer 4

an hypothesis perhaps? something to be proved?

Answer 5

i think thats what tfitz said lol

Answer 6

You should start with your givens. What you need to prove should follow from the things that you know.

Think of it kind of like answering three questions
1. What do I know?
2. What do the things I know tell me?
3. Does what I need to prove follow from 2?

That's how most direct proofs go. If you're doing a proof by contradiction though, you should substitute question one with
1. What if what I know is that what I need to prove is not true?