There are 5 essential parts in a good proof.

1. State the theorem to be proved
2. List the given information
3. If possible, draw a diagram to illustrate the situation and given information,
4.State what is to be proved
5. Develop a system of deductive reasoning.

In order to use deductive reasoning to construct a valid proof, we must rely on statements that are accepted to be true. In geometry, those statements are definitions and postulates. We also depend on a list of undefined terms.

Statements that are proved through deductive reasoning using definitions, postulates, and undefined terms are called theorems. Once a theorem is proved, it can be another tool that you can use in the system. That is, proved theorems can be used in the proof of new theorems.
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You usually just work with one side.

Add comments to every step that you think needs justification. That way, even if you go wrong, the reader knows where you’re going with the proof. Also remember to state theorems or identities used.