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arXiv · 2211.00186

A Proof Without Words: Triangles in the Triangular Grid

Peter Kagey
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Abstract

This proof without words demonstrates that there are $\binom{n+2}{4}$ equilateral triangles in the regular $n$-vertices-per-side triangular grid by describing a map from four-element subsets of $\{1,2, \dots, n+2\}$ into the set of equilateral triangles in this grid. Specifically, we illustrate the triangle that corresponds to the subset $\{4,5,8,11\}$ under this bijection when $n = 10$.

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Peter Kagey. 2022-10-31. A Proof Without Words: Triangles in the Triangular Grid. https://arxiv.org/abs/2211.00186

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