This document describes the structure and process of a two-column proof in geometry. A two-column proof has numbered statements in the left column with their corresponding reasons in the right column to logically prove a theorem. It provides an example to prove that all right angles are congruent using the given fact that angles X and Y are right angles.

1. Two-Column Proof Has numbered statements and reasons that show the logical order of an argument

2. Parts of a Two-Column Proof A diagram showing the given information. A list of the given information. A list of what is to be proved. A logical series of statements that lead from the given information to what is to be proved. The reasons why each statements is true. Reasons can include postulates, definitions, properties, previously stated theorems, or given facts.

3. Prove the theorem that all right angles are congruent. X Given: X and Y are right angles. Prove: X Y Proof: Y