九边形 Nonagon

（重定向自Enneagon）

九边形是几何学上所有有9条边和9只角的多边形。

正九边形是九边、九角相等的多边形。内角为140°。若边长为 $a$ ，面积 $A = \frac{9}{4}a^2 \cot \frac{\pi}{9} \approx 6.18182 a^2.$ 。若有正九边形 $ABCDEFGHI$ ， $AE=AB+AC$ 。它是继正七边形后另一个不能尺规作图的正多边形。

单词	enneagon
释义	enneagon /'eniəɡɔn/ 英汉-汉英词典 n. [数]九角形；九边形词组 \| 习惯用语您要查找的是不是： engineer n. 工程师；工兵；火车司机 vt. 策划；设计；精明地处理 pentagon n. 五角形 engender vt. 使产生；造成 vi. 产生；引起 wagoner n. 御夫座；车夫 enneagon n. 九角形；[数] 九边形网络短语: enneagon nonagon 九边形 enneagon ninogan 九角形 enneagon ĥ 九边形中文百科九边形 Nonagon （重定向自Enneagon）九边形是几何学上所有有9条边和9只角的多边形。正九边形是九边、九角相等的多边形。内角为140°。若边长为 $a$ ，面积 $A = \frac{9}{4}a^2 \cot \frac{\pi}{9} \approx 6.18182 a^2.$ 。若有正九边形 $ABCDEFGHI$ ， $AE=AB+AC$ 。它是继正七边形后另一个不能尺规作图的正多边形。英语百科 Nonagon 九边形（重定向自Enneagon） In geometry, a nonagon /ˈnɒnəɡɒn/ (or enneagon /ˈɛniːəɡɒn/) is a nine-sided polygon or 9-gon. 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 somewhat less common than "nonagon".
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enneagon /'eniəɡɔn/

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网络短语:

九边形 Nonagon

Nonagon 九边形