🌐EnglishEnglishEspañolFrançais中文日本語EntityQ7179251· pop 7· linked from 6 articlesPetr–Douglas–Neumann theoremAlso known as PDN-theorem, Douglas’s theorem, Douglas–Neumann theorem, Napoleon–Douglas–Neumann theorem, Petr’s theoremAvailable in 6 languagesFrançais中文日本語CzechHebrewvia Wikidata sitelinks · CC0ConnectionspentagonEntityPragueEntityCategoriesTheorems about quadrilaterals