Heptagon

A heptagon

A heptagon/septagon or 7-gon is a shape with 7 sides and 7 corners.

Regular heptagon

All sides of a regular heptagon are the same length. Each corner is about 147.27°. All corners added together are about equal to 6840°.

The amount of space a regular heptagon takes up is

[math]\displaystyle{ A = \frac{7}{4}a^2 \cot \frac{\pi}{7} \simeq 3.634 a^2. }[/math]

a is the length of one of its sides.

Neusis construction of a regular heptagon
Regular heptagon, animation, exact design, trisection of an angle by Tomahawk (blue)
Heptagon with given side length:*An animation from a neusis construction with marked ruler, according to David Johnson Leisk (Crockett Johnson).
Heptagone approximation
Symmetries of a regular heptagon. Vertices are colored by their symmetry positions. Blue mirror lines are drawn through vertices and edges. Gyration orders are given in the center.
a=red, b=blue, c=green lines
Heptagrams
The densest double lattice packing of the Euclidean plane by regular heptagons, conjectured to have the lowest maximum packing density of any convex set