Polygons

 Polygons

A polygon is a geometric shape located in a plane, consisting of straight edges that form a closed figure.

The term 'polygon' is derived from the Greek words 'poly,' meaning 'many,' and 'gonia,' meaning 'angle.

Is it a polygon or not?

The requirements for a shape to be a polygon are clearly given in the definition:

*In a plane

*Closed

*Straight edges




Polygons


Parts of a Polygon

Sides / Edges.

The straight line segments themselves are called sides, eg Hexagon has six sides / edges.



Vertices (Singular: Vertex):

The points where the line segments meet are called vertices. In a polygon, two line segments meet at each vertex.



Diagonals:

A diagonal is a line segment that connects two non-adjacent vertices.


Interior Angles




Regular or Irregular ?

Regular:  

*What we learn in schools and often use in daily life , For example, when we say pentagon, a shape resembling a single type comes to everyone's mind, but in fact, an infinite number of 5-sided shapes can be drawn.
*Has  specific properties, such as ;
 -- having equal interior angles 
-- sides that are equal to each other 




Irregular :

 In short, any polygon. ( Of course, a polygon cannot be both regular and irregular. )





Names of Polygons

Naming polygons is typically done based on the number of sides they have. Here's a general guide to naming polygons:

3 sides: Triangle

4 sides: Quadrilateral

5 sides: Pentagon

6 sides: Hexagon

7 sides: Heptagon

8 sides: Octagon

9 sides: Nonagon

10 sides: Decagon

11 sides: Undecagon or Hendecagon

12 sides: Dodecagon


For polygons with more than 12 sides, the naming can become more complex, and it's common to use the form "n-gon," where "n" is the number of sides. For example, a polygon with 20 sides can be referred to as a 20-gon.


Triangle 

A polygon with three angles and sides. "Tri-" comes from the Greek word for three.In Latino, 3 - Tres






Quadrilateral

From the Latin words "quadri" meaning four and "latus" meaning side.





Pentagon 

Pentagon (5 sides), From the Greek words "pente" meaning five and "gonia" meaning angle.




The Pentagon is the headquarters building of the United States Department of Defense. It's located in Arlington, Virginia, near Washington, D.C. The name "Pentagon" is derived from the shape of the building, which is a five-sided polygon known as a pentagon.


The Pentagon, U.S


Hexagon

From the Greek words "hex" meaning six and "gonia" meaning angle.



Heptagon  ( 7 Sides )


From the Greek words "hepta" meaning seven and "gonia" meaning angle.





Octagon (8 sides)

From the Greek words "okto" meaning eight and "gonia" meaning angle.




Nonagon (9 sides)

From the Latin word "nonus" meaning nine and the Greek word "gonia" meaning angle.

Nine corresponds to a Nonagon, making it easy to remember.



Decagon (10 sides)

 From the Greek words "deka" meaning ten and "gonia" meaning angle.



For polygons with more than ten sides, the names are often constructed using numerical prefixes combined with "-gon." For example:

Dodecagon (12 sides): 

From the Greek words "dodeka" meaning twelve and "gonia" meaning angle.

Icosagon (20 sides): 

From the Greek words "eikosi" meaning twenty and "gonia" meaning angle.

For very large numbers of sides, the naming can become more complex, and sometimes the term "n-gon" is used, where "n" is the number of sides (e.g., 100-gon for a 100-sided polygon).


How to remember ?

Some prefixes are commonly used in various scientific, mathematical, and everyday contexts to describe quantities, shapes, and concepts related to specific numbers.

2: "Di-" or "Bi-" "Dual"


Origin: "Di-" comes from the Greek "dis," meaning two, while "Bi-" comes from the Latin "bis," also meaning two.
Example: "Dichotomy" refers to a division into two parts; "Bicycle" refers to a vehicle with two wheels.
"Dual" comes from the Latin "duo," meaning two.
A dual-core processor has two processing cores, allowing it to handle two instructions simultaneously, improving performance.

3: "Tri-"


Origin: From the Greek "treis," meaning three.
Example: "Triangle" is a shape with three sides; "Tricycle" is a vehicle with three wheels.

4: "Tetra-" "Quad"


Origin: From the Greek "tettares," meaning four.
Example: "Tetrahedron" is a polyhedron with four faces; "Tetrapod" refers to vertebrates with four limbs.
"Quad" comes from the Latin "quattuor," meaning four.
A quad-core processor has four processing cores, enabling it to handle four instructions simultaneously, further enhancing performance.



5: "Penta-"


Origin: From the Greek "pente," meaning five.
Example: "Pentagon" is a shape with five sides; "Pentameter" refers to a line of verse consisting of five metrical feet. 
The Pentagon is the headquarters of the United States Department of Defense, located in Arlington, Virginia, just outside Washington, D.C. It's one of the world's largest office buildings, with about 6.5 million square feet of space.

6: "Hexa-"


Origin: From the Greek "hex," meaning six.
Example: "Hexagon" is a shape with six sides; "Hexachord" refers to a series of six musical notes.
A hexa-core processor has six processing cores, allowing for even more parallel processing of instructions.

8: "Octa-"


Origin: From the Greek "okto," meaning eight.
Example: "Octagon" is a shape with eight sides; "Octave" refers to a musical interval spanning eight notes.
An octo-core processor has eight processing cores, providing significant parallel processing capabilities for multitasking and demanding applications.

10: "Deca-"


Origin: From the Greek "deka," meaning ten.
Example: "Decade" refers to a period of ten years.

Are

An "are" is a unit of area that equals 100 square meters. 

Decare

 A "decare" is equal to 10 ar, or 1,000 square meters.

These units are used to measure land area in various contexts, such as agriculture, construction, and land planning. The prefix "deka-" in "dekar" specifically denotes a tenfold quantity, and it's an example of how numerical prefixes are used in the naming of units of measurement.

Deca-core processor
A "deca-core processor" refers to a computer processor that has ten individual processing cores. 

More ...

Regular Polygons

Geometry Index


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