en.wikipedia.org/wiki/Hendecagon

In geometry, a hendecagon (also undecagon or endecagon) or 11-gon is an eleven-sided ... A regular hendecagon has internal angles of 147.27 degrees. The area of a regular hendecagon with side length a is given by. A = 11 4 a 2 cot π ...

en.wikipedia.org/wiki/List_of_polygons

A regular pentagon has 5 equal edges and 5 equal angles. In geometry, a polygon /ˈpɒlɪɡɒn/ is traditionally a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed chain or circuit. These segments are called its edges or sides, and the points where two ... eleven , eleventh, hendeka, hendekatos.

www.math.com/tables/geometry/polygons.htm

What is a Polygon? A closed plane figure made up of several line segments that are joined together. The sides do not cross each other. Exactly two sides meet ...

www.reference.com/math/11-sided-shape-called-2f7f8996d4b356d2

An 11-sided shape is called a hendecagon. The name is derived from the Greek ... A: A nonagon is a closed shape that has nine sides. If it is a regular nonagon, ...

mathcentral.uregina.ca/qq/database/qq.09.96/rosa1.html

... different names? Thank you for your help. Hi Manuel. There seems to be an " official"set of names for polygons, uniformly derived from the Greek (after 4 sides) .

answers.yahoo.com/question/index?qid=20061121092221AANGCFa

Best Answer: Polygon names Name Sides : henagon (or monogon) 1 digon 2 triangle (or trigon) 3 quadrilateral (or tetragon) 4 pentagon 5

www.mathsisfun.com/shape.html

2D Shapes. Regular Polygons. A polygon is a plane (2D) shape with straight sides. To be a regular polygon all the sides and angles must be the same: ...

en.wikibooks.org/wiki/Geometry_for_Elementary_School/Plane_shapes

A shape with only straight sides as edges is called a polygon(POL-ee-gone). Polygons must .... Hendecagons (also known as undecagons) have eleven sides.

faculty.kutztown.edu/schaeffe/Tutorials/General/Polygons.html

For polygons with 3 through 20 sides, simply add "gon" to the prefixes at the left ( although a trigon is more commonly called a triangle and a tetragon, ...