Enneagon Dissections

Author : Gavin Theobald

{3} Triangle
{4} Square
{5} Pentagon
{6} Hexagon
{7} Heptagon
{8} Octagon
{10} Decagon
{12} Dodecagon
{18} Octadecagon
{5/2} Pentagram
{6/2} Hexagram
{8/2} Octagram
{8/3} Octagram
{9/2} Enneagram
{9/3} Enneagram
{10/2} Decagram
{12/2} Dodecagram
{18/2}  Octadecagram
{R√2} Silver Rectangle
{Rϕ} Golden Rectangle
{R2} Domino
{R×} Optimised Rectangle
{G} Greek Cross
{L} Latin Cross
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
8 9 10 1110 13 12 1 13 1413 19


5/2 6/2 7/2 7/3 8/2 8/3 9/2 9/3 9/4 10/2 10/3 10/4 12/2 12/3 12/4 12/5
14 11 15 13 19  19 17 14


Triangle — Enneagon (8 pieces)

This dissection makes use of the TT2 technique.

Previously Freese found a 9 piece solution to this dissection. In Lindgren's book he states “The conclusion is that if you can beat Freese, you will have found a needle in a haystack”. I found the needle! This was one of the first dissection improvements that I found, and I am particularly pleased with it.


Square — Enneagon (9 pieces)


Pentagon — Enneagon (10 pieces)


Hexagon — Enneagon (11 pieces)

Hexagon — Enneagon (10 pieces with 1 turned over)


Heptagon — Enneagon (13 pieces)


Octagon — Enneagon (12 pieces)


Enneagon — Decagon (13 pieces)


Enneagon — Dodecagon (14 pieces)

Enneagon — Dodecagon (13 pieces with 3 turned over)


Enneagon — Octadecagon (19 pieces)


Enneagon — Pentagram (14 pieces)


Enneagon — Hexagram (11 pieces)


Enneagon — Octagram {8/2} (15 pieces)


Enneagon — Octagram {8/3} (13 pieces)


Enneagon — Enneagram {9/2} (19 pieces)


Enneagon — Enneagram {9/3} (19 pieces with 9 turned over)

Discovered by Greg Frederickson (2002).


Enneagon — Decagram {10/2} (17 pieces)


Enneagon — Dodecagram {12/2} (14 pieces)


Enneagon — Octadecagram {18/2} (17 pieces)


Enneagon — Silver Rectangle (9 pieces)


Enneagon — Golden Rectangle (9 pieces)


Enneagon — Domino (9 pieces)


Enneagon — Optimised Rectangle (7 pieces)


Enneagon — Greek Cross (11 pieces)


Enneagon — Latin Cross (10 pieces)