Nonagon

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In geometry, a nonagon () or enneagon () is a nine-sided polygon or 9-gon. The total sum of a simple nonagon's interior angles is 1260°. The name nonagon is a prefix hybrid formation, from Latin (nonus, "ninth" + gonon), used equivalently, attested already in the 16th century in French nonogone and in English from the 17th century. The name enneagon comes from Greek enneagonon (εννεα, "nine" + γωνον (from γωνία = "corner")), and is arguably more correct, though less common.

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