# 2D shapes – Nonagon

A nonagon is a two-dimensional (2D) shape that consists of nine straight sides and nine angles. It is a polygon, which is a closed figure made up of straight lines. The prefix “nona-” means nine, reflecting the defining characteristic of a nonagon.

Key Features of a Nonagon:

1. Sides: A nonagon has nine sides. All the sides are equal in length, meaning they have the same measurement.
2. Angles: A nonagon has nine angles. Each angle is formed where two sides meet. The sum of the interior angles in any nonagon is always 1440 degrees.
3. Symmetry: A nonagon has multiple lines of symmetry. It can be divided into nine equal sectors by lines passing through its center, connecting the vertices to the midpoint of the opposite side. Additionally, it has rotational symmetry of order 9, meaning it looks the same after being rotated by multiples of 40 degrees (360 degrees divided by 9).
4. Regular and Irregular Nonagons: If all the sides and angles of a nonagon are equal, it is called a regular nonagon. Otherwise, it is referred to as an irregular nonagon.

Properties and Uses:

1. Perimeter: The perimeter of a nonagon is the total length of its nine sides. To find the perimeter, you can add the lengths of all the sides together.
2. Geometry and Mathematics: Nonagons are studied in geometry and have applications in various mathematical concepts. They can be used in tessellations, where nonagons are combined to form repeating patterns without any gaps or overlaps.
3. Art and Design: The unique shape of a nonagon can be aesthetically pleasing and is often used in art and design. It can be incorporated into architectural designs, decorative patterns, and artistic compositions.
4. Practical Applications: Although less common than other polygons, nonagons can be found in certain real-life objects or structures. For example, some clocks or dials may have nonagon shapes for hour indicators.