You're in luck! It hasn't ever been given a name by anyone else,
so you're free to call it by any name you like.
The reason is: It doesn't exist. A "pentagon" has five sides,
so there aren't any with 20 sides, and there never will be.
It is a Pentagon.
A 5 sided shape is a pentagon. Its perimeter has no relevance.
There is no such thing as a nine sided pentagon. A pentagon has 5 sides; no more, no less.
A pentagon is a 5 sided polygon
A five sided shape is called a pentagon.
pentagon
840
A five sided polygon is called a pentagon because pentagon means five sided polygon I think.
The name of a 5 sided polygon is Pentagon.
a pentagon
pentagon
Pentagon.