## Is it a Polygon?

Polygons space 2-dimensional shapes. They space made of directly lines, and the form is "closed" (all the lines attach up).

 Polygon(straight sides) Not a Polygon(has a curve) Not a Polygon(open, no closed)

## Types that Polygons

### Regular or Irregular

A regular polygon has actually all angles equal and also all political parties equal, otherwise it is irregular

 Regular Irregular

### Concave or Convex

A convex polygon has actually no angles pointing inwards. Much more precisely, no internal angle deserve to be much more than 180°.

If any type of internal angle is greater than 180° climate the polygon is concave. (Think: concave has a "cave" in it)

 Convex Concave

### Simple or Complex

A simple polygon has actually only one boundary, and it doesn"t cross end itself. A complex polygon intersects itself! countless rules around polygons don"t work when that is complex.

 Simple Polygon(this one"s a Pentagon) Complex Polygon(also a Pentagon)

## More Examples

 Irregular Hexagon Concave Octagon Complex Polygon(a "star polygon",in this instance a pentagram)

## Play with Them!

Try Interactive polygon ... Make them regular, concave or complex.

## Names that Polygons

NameSidesShapeInterior Angle
 If that is a continuous Polygon... Triangle (or Trigon) 3 60° Quadrilateral (or Tetragon) 4 90° Pentagon 5 108° Hexagon 6 120° Heptagon (or Septagon) 7 128.571° Octagon 8 135° Nonagon (or Enneagon) 9 140° Decagon 10 144° Hendecagon (or Undecagon) 11 147.273° Dodecagon 12 150° Triskaidecagon 13 152.308° Tetrakaidecagon 14 154.286° Pentadecagon 15 156° Hexakaidecagon 16 157.5° Heptadecagon 17 158.824° Octakaidecagon 18 160° Enneadecagon 19 161.053° Icosagon 20 162° Triacontagon 30 168° Tetracontagon 40 171° Pentacontagon 50 172.8° Hexacontagon 60 174° Heptacontagon 70 174.857° Octacontagon 80 175.5° Enneacontagon 90 176° Hectagon 100 176.4° Chiliagon 1,000 179.64° Myriagon 10,000 179.964° Megagon 1,000,000 ~180° Googolgon 10100 ~180° n-gon n (n−2) × 180° / n

You can make names utilizing this method:

 Sides Start with... 20 Icosi... 30 Triaconta... 40 Tetraconta... 50 Pentaconta... 60 Hexaconta... 70 Heptaconta... 80 Octaconta... 90 Enneaconta... 100 Hecta... etc..See more: Strengths And Weaknesses: North Advantages During The Civil War

Sides
...end with
+1
...henagon
+2
...digon
+3
...trigon
+4
...tetragon
+5
...pentagon
+6
...hexagon
+7
...heptagon
+8
...octagon
+9
...enneagon

Example: a 62-sided polygon is a Hexacontadigon

BUT, because that polygons v 13 or more sides, it is ok (and easier) to write "13-gon", "14-gon" ... "100-gon", etc.

## Remembering

A Quad Bike has 4 wheels

### Pentagon (5 Sides)

The "Pentagon" in Washington DC has 5 sides

### Hexagon (6 Sides)

Honeycomb has Hexagons

### Septagon (7 Sides)

Think Septagon is a "Seven-agon"

### Octagon(8 Sides)

An Octopus has 8 tentacles

### Nonagon (9 Sides)

Think Nonagon is a "Nine-agon"

### Decagon (10 Sides)

Think Decagon has actually 10 sides,just choose our Decimal system has actually 10 digits

interactive Polygons internal Angles of polygons Exterior angles of polygon 2D shapes (simpler page)