Pentagon

In geometry, a pentagon is any five-sided polygon.

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However, the term is commonly used to mean a regular pentagon, where all sides are equal and all angles are equal (to 108?). Its Schl?fli symbol is {5}.

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The area of a regular pentagon with side length a is given by

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A = rac{5a^2}{4}cot rac{pi}{5} = rac {a^2}{4} sqrt{25+10sqrt{5}} simeq 1.72048 a^2

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A pentagram can be formed from a regular pentagon either by extending its sides or by drawing its diagonals, and the resulting figure contains various lengths related by the golden ratio, φ = (1+√5)/2.

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Geometry: Geometry (Greek Γεωμετρια, geo = earth, metria = measure) arose as the field of knowledge dealing with spatial relationships. It was one of the two fields of pre-modern mathematics, the other being the study of numbers. In modern times, geometric c...

Polygon: :For other use please see Polygon (disambiguation)...

Pentagram: :This article is about the geometric design. For other meanings, see Pentagram (disambiguation)...

Pentagon related Images and Photos (experimental)

Pentagon Wars, The (DVD)	Pentagon Arlington Virginia USA	12 Surface IQ Pentagon	Pentagon's O'Beirne and Randall Sending Test Document on Wash-Moscow Direct Communications Link
General John Shalikashvili Swearing-In as Chairman of Joint Chiefs of Staff in Pentagon Ceremony	US General Shalikashvili in His Swear-In as Chariman of Joint Chiefs of Staff Pentagon Ceremony