Definition: A polygon with 7 sides

also: Septagon

also: Septagon

Try this
Adjust the heptagon below by dragging any orange dot. By clicking on the top left command line,
you can switch it between a
regular and
irregular heptagon.

Interior angle | 128.571° | Like any regular polygon, to find the interior angle we use the formula (180n–360)/n . For a heptagon, n=7. See Interior Angles of a Polygon |

Exterior Angle | 51.429° | To find the exterior angle of a regular heptagon, we use the fact that the exterior angle forms a linear pair with the interior angle, so in general it is given by the formula 180-interior angle. See Exterior Angles of a Polygon |

Area | 3.633s^{2}approx | Where S is the length of a side. To find the exact area of a heptagon or any polygon, using various methods, see Area of a Regular Polygon and Area of an Irregular Polygon |

Number of diagonals | 14 | The number of distinct diagonals possible from all vertices. (In general ½n(n–3) ). In the figure above, click on "show diagonals" to see them. See Diagonals of a Polygon |

Number of triangles | 5 | The number of triangles created by drawing the diagonals from a given vertex. (In general n–2). In the figure above, click on "show triangles" to see them. See Triangles of a Polygon |

Sum of interior angles | 900° | In general 180(n–2) degrees . See Interior Angles of a Polygon |

Heptagons are not seen much in everyday life except in the UK, where there are coins in the shape of a heptagon.
On the right is the 50 pence coin. It is not a strict heptagon because the sides are actually curved arcs instead of straight lines.
The resulting shape is known as an "Equilateral Curve Heptagon".

It has one very curious property; in spite of not being a circle it has the same diameter everywhere!
This is done so that it will always fit
in coin-operated machines, but still feel different in the hand from
other round coins - a help to sight-impaired people.

- Polygon general definition
- Quadrilateral
- Regular polygon
- Irregular polygon
- Convex polygons
- Concave polygons
- Polygon diagonals
- Polygon triangles
- Apothem of a regular polygon
- Polygon center
- Radius of a regular polygon
- Incircle of a regular polygon
- Incenter of a regular polygon
- Circumcircle of a polygon
- Parallelogram inscribed in a quadrilateral

- Square
- Diagonals of a square
- Rectangle
- Diagonals of a rectangle
- Golden rectangle
- Parallelogram
- Rhombus
- Trapezoid
- Trapezoid median
- Kite
- Inscribed (cyclic) quadrilateral

- Regular polygon area
- Irregular polygon area
- Rhombus area
- Kite area
- Rectangle area
- Area of a square
- Trapezoid area
- Parallelogram area

- Perimeter of a polygon (regular and irregular)
- Perimeter of a triangle
- Perimeter of a rectangle
- Perimeter of a square
- Perimeter of a parallelogram
- Perimeter of a rhombus
- Perimeter of a trapezoid
- Perimeter of a kite

- Exterior angles of a polygon
- Interior angles of a polygon
- Relationship of interior/exterior angles
- Polygon central angle

- Tetragon, 4 sides
- Pentagon, 5 sides
- Hexagon, 6 sides
- Heptagon, 7 sides
- Octagon, 8 sides
- Nonagon Enneagon, 9 sides
- Decagon, 10 sides
- Undecagon, 11 sides
- Dodecagon, 12 sides

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