What is the names of shapes with 13 to 20 sides?
Shapes with 13 to 20 sides are known as polygons. Specifically, a 13-sided polygon is called a tridecagon, a 14-sided polygon is called a tetrakaidecagon, a 15-sided polygon is called a pentadecagon, a 16-sided polygon is called a hexadecagon, a 17-sided polygon is called a heptadecagon, an 18-sided polygon is called an octadecagon, a 19-sided polygon is called an enneadecagon, and a 20-sided polygon is called an icosagon.