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Videos, worksheets, games and activities to help Grade 9, Geometry students learn how to use two column proofs.

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More Geometry Lessons

Two column proofs are organized into statement and reason columns. Each statement must be justified in the reason column. Before beginning a two column proof, start by working backwards from the "prove" or "show" statement. The reason column will typically include "given", vocabulary definitions, conjectures, and theorems.

How to organize a two column proof.

Writing Your First Two-Column Proof

This video outlines the process for writing a flow and two-column proof.

Geometry Proofs - Two Column Proofs

Students learn to set up and complete two-column Geometry proofs using the properties of equality as well as postulates and definitions from Geometry.

Two column proof showing segments are perpendicular

Using triangle congruency postulates to show that two intersecting segments are perpendicular.

This video provides a two column proof of the isosceles triangle theorem.

This video provides a two column proof of the exterior angles theorem.

Geometric Proofs

Learn to prove geometric statements using two column proofs.