A decagon is a polygon that has ten sides and ten angles. The word "decagon" comes from the Greek words "deka," meaning ten, and "gonia," meaning angle. Each interior angle in a regular decagon measures 144 degrees, and the total sum of all interior angles is 1,440 degrees. Decagons can be found in various shapes, including regular decagons, where all sides and angles are equal, and irregular decagons, which have sides and angles of different lengths. Decagons are often studied in geometry, a branch of mathematics that deals with shapes and their properties. They can also be seen in real life, such as in the design of certain buildings or objects, like a stop sign that has an oct