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PROVED This has been solved in the affirmative.
If $A,B,C\in \mathbb{R}^2$ form a triangle and $P$ is a point in the interior then, if $X$ where the perpendicular from $P$ to $AB$ meets the triangle, and similarly for $Y$ and $Z$, then\[\overline{PA}+\overline{PB}+\overline{PC}\geq 2(\overline{PX}+\overline{PY}+\overline{PZ}).\]
Conjectured by Erdős in 1932 (according to [Er82e]) and proved by Mordell soon afterwards, now known as the Erdős-Mordell inequality.

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When referring to this problem, please use the original sources of Erdős. If you wish to acknowledge this website, the recommended citation format is:

T. F. Bloom, Erdős Problem #898, https://www.erdosproblems.com/898, accessed 2025-11-15
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