Why do you do proofs in geometry?

You start out with things that you know and use them to make logical arguments about what you want to prove. The things you know may be axioms, or may be things you already proved and can use.

The practice of doing Geometry proofs inspires logical thinking, organization, and reasoning based on facts. Each statement must be supported with a valid reason, which could be a given fact, definitions, postulates, or theorems.