What is a Two-Column Proof?
A **two-column proof** is a formal way to organize a deductive argument in geometry. It's used to prove that a geometric statement is true based on a set of given facts and logical reasoning. A proof consists of two columns:
- The **Statements** column contains a logical sequence of assertions. Each statement follows directly from the previous ones.
- The **Reasons** column provides the justification for each statement. Reasons can be given information, definitions, postulates, or previously proven theorems.
The first statement is always the **Given** information, and the last statement is the **Conclusion** (the statement you are trying to prove).
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Video: How to Write a Two-Column Proof!
Watch this video to learn the step-by-step process of creating a two-column proof. 🎥
Practice Problems
Match the reason to the statement to complete the proofs!
Statement: $AB = BC$
Statement: $\angle1 \cong \angle2$
Statement: $PQ + QR = PR$
Statement: $\triangle ABC \cong \triangle DEF$
⚡ Proof Reasons Speed Quiz
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