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

A two-column proof consists of a list of statements, and the reasons why those statements are true. The statements are in the left column and the reasons are in the right column. The statements consists of steps toward solving the problem.

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More Geometry Lessons

Proof Practice 1

Practice writing a 2 column proof.

Proof Practice 2

Practice writing two column proofs.

Proof Practice 3

Practice writing two column proofs.

Practice Proof 4

Practice writing 2 column proofs.

Two column proof showing segments are perpendicular

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

Two column proof to prove parallel lines.

Proving a Quadrilateral a Parallelogram | Geometry Proof

This video geometry lesson proves two parallelogram theorems.

Proof 1: If the diagonals of a quadrilateral bisect each other, then the quadrilateral is a parallelogram.

Proof 1: If both pairs of opposite sides of a quadrilateral are congruent, then the quadrilateral is a parallelogram.

Theorems Used: If both pairs of opposite angles of a quadrilateral are congruent, then the quadrilateral is a parallelogram and If one pair of opposite sides of a quadrilateral is both congruent and parallel, then the quadrilateral is a parallelogram to solve problems.

Special Parallelograms Part 2 Rhombus and Rectangle Proofs

This video uses the two column method to prove two theorems.

Proof 1: The diagonals of a rectangle are congruent. This amounts to be a triangle proof to use CPCTC.

Proof 2: The diagonals of a rhombus are perpendicular.