# Proof by Contradiction

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More Lessons for High School Regents Exam

Math Worksheets

High School Math based on the topics required for the Regents Exam conducted by NYSED.

How to Proof by Contradiction (also called Indirect Proof)?
Suppose we want to prove S
1. Assume not S.
2. Try to find a contradiction by the implications of not S. (Show that not S is false)
3. If we find a contradiction then we can accept S to be true since not S is false.

Proof that $$\sqrt 2$$ is irrational

Indirect Proof: Lesson (Geometry Concepts)
In this lesson, you'll learn how to write indirect proofs, or proofs by contradiction, by assuming a hypothesis is false.
Indirect Proof: Examples
This video shows how to work step-by-step through two examples in Indirect Proof.

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