**A shape that has 10 sides is call a decagon.** A decagon is a type of polygon, which is a two dimensional shape with straight lines. These lines connect to each other to form a closed shape.

There are several types of decagons. An equilateral decagon is a decagon with equal length sides while an equiangular decagon has equal angles. A regular decagon has equal angles of 144 degrees each and sides of the same length. If the sides or angles are not equal, then the decagon is irregular. If none of the internal angles are greater than 180 degrees, then it is a convex decagon. If at least one angle is greater than 180 degrees, then the decagon is convex.