Naming Polygons

HOMEWORK: Complete ‘Name That Polygon’ Activities WS

Naming a polygon by its number of sides requires that we know the appropriate Greek prefixes along

with some rules for their use.

3 = tri4 = tetra5 = penta6 = hexa or sexa7 = hepta8 = octa9 = nona

10 = deca11 = undeca 12 = dodeca13 = triskaideca14 = tetradeca15 = pentadeca16 = hexadeca17 = heptadeca18 = octadeca19 = enneadeca20 = icosa

For polygons with 3 through 20

sides, simply add "gon" to the prefixes to

the right - although a trigon is more commonly called a triangle and a tetragon, a quadrilateral!

21 - 99 SIDESTo "construct" a name, we start with the prefix for the

tens digit, follow it by "kai" (the Greek word for "and"), then follow it with the prefix for the units digit,

and finally add "gon."

Example: A 35-sided polygon is called a "triacontakaipentagon."

30 and 5 gon

triaconta kai penta gon

Tens Digit20 = icosi30 = triaconta40 = tetraconta50 = pentaconta60 = hexaconta70 = heptaconta80 = octaconta90 = enneaconta

Ones Digit1 = hena2 = di3 = tri4 = tetra5 = penta6 = hexa7 = hepta8 = octa9 = ennea

+

For more than 20 sides, we "construct" the name by combining prefixes:

25 = icosi + kai + penta+ gon = icosikaipentagon

77 = heptaconta + kai + hepta + gon = heptacontakaiheptagon

100 - 999 SIDESFor numbers from 100 to 999, we need one more combining prefix

and another rule.To "construct" the name, we start with the prefix for the hundreds digit taken from the "Ones Digit" table above, follow it by "hecta,"

then proceed as before.

Example: A 672-sided polygon is called a "hexahectaheptacontakaidigon."

100 = hecta

600 70 and 2 gonhexa + hecta heptaconta kai di gon

Now you try some

914 sides

75 sides

753 sides

Triskaidecagon 13

Tetrakaidecagon 14

Pentadecagon 15

Hexakaidecagon 16

Heptadecagon 17

Octakaidecagon 18

Enneadecagon 19

Icosagon 20

Triacontagon 30

Tetracontagon 40

Pentacontagon 50

Hexacontagon 60

Heptacontagon 70

Octacontagon 80

Enneacontagon 90

Hectagon 100

Chiliagon 1,000

Myriagon 10,000

Megagon 1,000,000

Googolgon 10100

Hectagon 100

Chiliagon 1,000

Myriagon 10,000

Megagon 1,000,000

Googolgon 10100

Enneahectaenneacontakaienneagon

How many sides??

Tetracontakaihexagon

Icosikaioctagon

Octacontakaihexagon

Heptacontakaitrigon

Octacontakaitrigon

Dihectapentacontakaiheptagon