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The Basics of a Pentadecagon

The Basics of a Pentadecagon

Author: Angela McGuire

To introduce people to the basics of a pentadecagon.

A pentadecagon is a fifteen sided and fifteen angled polygon.

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What is a Pentadecagon?


A pentadecagon in Geometry is any 15 sided, 15 angled polygon and the sum of its interior angles will always be 2340 degrees.


The name pentadecagon is derived from the names of smaller polygons. Penta means five and is derived from the pentagon with five sides. Deca means ten and we have the decagon a ten sided polygon. A pentadecagon is a fifteen sided polygon, which can be understood from its name because of penta meaning five and deca meaning ten, put them together and its fifteen.


In this packet I am going to tell you about the basics of a pentadecagon.


This Includes:


-What it is


-What qualifies as one



Let's Review what I said earlier. That a pentadecagon is a 15 sided and 15 angles polygon and its interior angles sum equals 2340 degrees.

A pentadecagon is not a shape we see in everyday life. We can see triangles in pizza slices and yield signs or we can see squares in window frames or rectangles in books, but pentadecagons are not a typical shape we see in everyday life.

Example of Things Mistaken for a Pentadecagon

*Many people will mistake other larger polygons for a pentadecagon, such as, a hexadecagon ( 16 sided shape). This works Both ways. Sometimes people will skip the counting of sides and call all larger polygons they see by one name.

*Another common error is people will forget the basic rule fro polygons and forget that it needs to be a shape with no opening. So, sometimes people will see 15 sides and think, "That's a pentadecagon." That is why it is important to always remember the basics of polygons.




Requirments of a Pentadecagon

For this we need to go back to its definition. A pentadecagon is a 15 sided and 15 angled polygon.

So, the requirements of being a pentadecagon is simple; it needs 15 sides, 15 angles, and it has to have straight lines and be a closed shape, like any other polygon.



Other Examples:

Pentadecagon Reveiw Video


The most important thing to remember is a polygon is a figure with three or more sides, that are straight, and come to a close.

So, when it comes to looking at a pentadecagon it is important to remember the definition of a polygon and to take into consideration it only has fifteen sides and fifteen angles.

A pentadecagon is not just a shape, there are hundreds of different pentadecagons out there, it is just a matter of finding them.


*For anyone who wants a review or a review game on the basics of polygons and their main concepts. (Like a triangle has three angles or what a trapezoid may look like). Here is a link to a game that can give you a basic review.

*This same website has several other games to offer for review on mathematical cncepts.