A decagon is a polygon with 10 sides, and it is one of the many fascinating shapes in geometry. The word "decagon" comes from the Greek words "deka," meaning 10, and "gon," meaning angle. A decagon has 10 vertices and 10 sides, and the sum of its internal angles is 1,440 degrees. In this article, we will delve into the properties and characteristics of a decagon, exploring its various aspects and applications.
Properties of a Decagon

A regular decagon is a decagon with all sides and angles equal. It has 10-fold rotational symmetry, meaning that it looks the same after a rotation of 36 degrees. The internal angles of a regular decagon are all equal, each measuring 144 degrees. The external angles, on the other hand, are all equal to 36 degrees. A decagon can be inscribed in a circle, and its vertices can be connected to form a regular decagon.
Types of Decagons
There are several types of decagons, including regular decagons, irregular decagons, and convex decagons. A regular decagon is a decagon with all sides and angles equal, while an irregular decagon has sides and angles of different lengths and measures. A convex decagon is a decagon where all internal angles are less than 180 degrees. Decagons can also be classified as cyclic or non-cyclic, depending on whether they can be inscribed in a circle.
| Property | Value |
|---|---|
| Number of sides | 10 |
| Number of vertices | 10 |
| Sum of internal angles | 1,440 degrees |
| Internal angle measure | 144 degrees |
| External angle measure | 36 degrees |

Key Points
- A decagon is a polygon with 10 sides and 10 vertices.
- The sum of the internal angles of a decagon is 1,440 degrees.
- A regular decagon has 10-fold rotational symmetry and all sides and angles equal.
- Decagons can be classified as regular, irregular, convex, or non-convex.
- Decagons have many real-world applications, including architecture, engineering, and design.
Real-World Applications of Decagons

Decagons are used in various fields, including architecture, engineering, and design. They are often used in the construction of buildings, bridges, and other structures, due to their unique properties and characteristics. Decagons are also used in art and design, where they are used to create intricate patterns and shapes. In addition, decagons are used in mathematics and science, where they are used to model and analyze complex systems and phenomena.
Mathematical Properties of Decagons
Decagons have many interesting mathematical properties, including their symmetry and tessellations. A decagon can be tessellated, or covered, with smaller shapes, such as triangles or hexagons. Decagons can also be used to create fractals, or self-similar patterns, by repeating a shape over and over again. In addition, decagons have many geometric properties, including their perimeter, area, and volume.
In conclusion, decagons are fascinating shapes with many unique properties and characteristics. They have many real-world applications, including architecture, engineering, and design, and are used in various fields, including mathematics and science. Whether you are an architect, engineer, or artist, decagons are a shape worth exploring and learning more about.
What is a decagon?
+A decagon is a polygon with 10 sides and 10 vertices.
What are the properties of a regular decagon?
+A regular decagon has all sides and angles equal, with 10-fold rotational symmetry.
What are the real-world applications of decagons?
+Decagons are used in various fields, including architecture, engineering, and design, due to their unique properties and characteristics.