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Proof Without Words: a² - b² = (a + b)(a - b) via Isosceles Triangle and Right Trapezoid

Abstract

The difference of the areas of two similar isosceles right triangles equals the area of a right trapezoid, providing a visual proof of the algebraic identity a² - b² = (a + b)(a - b). The argument requires only the standard area formulas for a triangle and a trapezoid, offering teachers a simpler alternative to existing proofs of this identity.

Keywords

Isosceles Triangle, Right Trapezoid, Visual Reasoning

How to Cite

Mahmood, M., (2026) “Proof Without Words: a² - b² = (a + b)(a - b) via Isosceles Triangle and Right Trapezoid”, Ohio Journal of School Mathematics 103(1): 7, 86-87. doi: https://doi.org/10.18061/ojsm.6915

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Authors

Munir Mahmood (Mathematics and Statistics Education Australia)

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Creative Commons Attribution-NoDerivatives 4.0

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This article has been peer reviewed.

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