Icosagon is a 20 sided figure.
The name of a four sided figure (or shape) is called a Square. :)
The name that is given to an 8 sided figure is a octogan.
A 5 sided figure is called a: pentagon
A 15-sided figure is called a pentadecagon.
The name of am 11-sided figure is a "hendecagon". ---- Also known as an "undecagon".
A 5-sided 2-dimensional figure is a pentagon and a 5-sided 3-dimensional shape is a pentahedron.
A 5-sided figure is called a pentagon.
Heptagon - a seven sided two demensional figure
A six sided polygon is an hexagon
In 2 dimensions, a regular 5 sided figure is a pentagon. In 3 dimensions, there is no regular sided 5 sided figure. The tetrahedron is a regular 4 sided figure and a cube is a regular 6 sided figure.
Dodeca-, meaning 2+10, is used in describing any 12-sided figure thus dodecagon