Pythagorean Theorem

09 May 2026, Version 1
This content is an early or alternative research output and has not been peer-reviewed by Cambridge University Press at the time of posting.

Abstract

The document presents a proof attempt for the Pythagorean Theorem, starting from the assumption that a right triangle with legs a and b and hypotenuse c might violate the relation 𝑐 2 = π‘Ž 2 + 𝑏 2 . The author explores two cases: Assuming 𝑐 2 > π‘Ž 2 + 𝑏 2 The document shows that this leads to contradictions with the triangle inequality 𝑐 < π‘Ž + 𝑏. Several algebraic decompositions of the excess term π‘Ÿ are tested, each producing a contradiction such as 𝑐 = π‘Ž + 𝑏, which is impossible for a non-degenerate triangle. Assuming 𝑐 2 < π‘Ž 2 + 𝑏 2 Similarly, this assumption leads to contradictions with the fact that the hypotenuse must be the longest side. Decompositions of the deficit term again produce impossible results such as 𝑐 = π‘Ž βˆ’ 𝑏 or 𝑐 < π‘Ž. Because both alternatives lead to contradictions, the document concludes that the only consistent possibility is: β€œπ‘ 2 = π‘Ž 2 + 𝑏 2” (from the document: β€œ: c2 = a2 + b2 ... by A & B”) Thus, the proof uses proof by contradiction to establish the Pythagorean Theorem

Keywords

Pythagorean Theorem Right triangle Hypotenuse Proof by contradiction Triangle inequality Algebraic decomposition Geometric proof Real numbers Euclidean geometry

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