Pentagon Dissections

Author : Gavin Theobald

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{3} Triangle
{4} Square
{6} Hexagon
{7} Heptagon
{8} Octagon
{9} Enneagon
{10} Decagon
{11} Hendecagon
{12} Dodecagon
{5/2} Pentagram
{6/2} Hexagram
{8/2} Octagram
{8/3} Octagram
{12/2}  Dodecagram


Triangle - Pentagon Triangle - Pentagon

Triangle - Pentagon (6 pieces)

This is perhaps not the best example of a dissection of triangle and pentagon, but it is new and it does demonstrate the TT22 technique.


Square - Pentagon Square - Pentagon

Square - Pentagon (6 pieces)

This is not a very elegant solution because of the rather small piece, but it is another example of a TT22 dissection. There are a number of different six piece solutions possible and this raises the question of whether or not a five piece solution exists. There is a range of rectangle shapes that will dissect to a pentagon in just five pieces, but I think it unlikely that anyone will find a five piece solution for the square.


Pentagon - Hexagon Pentagon - Hexagon

Pentagon - Hexagon (7 pieces)

Discovered by Harry Lindgren (1964).


Pentagon - Heptagon Pentagon - Heptagon

Pentagon - Heptagon (9 pieces)


Pentagon - Octagon Pentagon - Octagon

Pentagon - Octagon (9 pieces)

Pentagon - Octagon Pentagon - Octagon

Pentagon - Octagon (8 pieces with 1 turned over)


Pentagon - Enneagon Pentagon - Enneagon

Pentagon - Enneagon (10 pieces)


Pentagon - Decagon Pentagon - Decagon

Pentagon - Decagon (9 pieces)

I nearly missed finding this dissection. The grey piece is no nearly cut into two, adding another two pieces to this dissection, that I did not think that it was possible. Fortunately I checked and hence obtained another record.


Pentagon - Hendecagon
Pentagon - Hendecagon
Pentagon - Hendecagon

Pentagon - Hendecagon (12 pieces)

The overlay diagrams on the right show the basic dissection before I modify it to save some pieces.


Pentagon - Dodecagon Pentagon - Dodecagon

Pentagon - Dodecagon (10 pieces)

There is room for improvement in this dissection. Is a 9 piece solution possible?


Pentagon - Pentagram Pentagon - Pentagram

Pentagon - Pentagram (9 pieces)


Pentagon - Hexagram Pentagon - Hexagram

Pentagon - Hexagram (8 pieces)

This is another example of a TT22 dissection.


Pentagon - Octagram Pentagon - Octagram

Pentagon - Octagram (11 pieces)


Pentagon - Octagram Pentagon - Octagram

Pentagon - Octagram (9 pieces)

The thin spike makes this a rather inelegant dissection, but I have not been able to find another 9 piece solution.


Pentagon - Dodecagram Pentagon - Dodecagram

Pentagon - Dodecagram (12 pieces)

Compared to the other dodecagram dissections this one is particularly inefficient. This is due to the dimensions of the pentagon making it impractical to form a pentagon tessellation that can overlay a dodecagram tessellation.


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