Questions tagged [dissection]
Problems that involve partitioning a geometric figure into smaller pieces with certain conditions on them (equal area, equal shape, possible to be rearranged into another given figure, etc.)
69 questions
1 vote
1 answer
129 views
Coincidences related to a dissection of the regular octagon
Is there some "unifying explanation" of existence of this interesting dissection of a side-1 regular octagon into six side-1 quadrilaterals (two squares and four rhombi) and the following ...
21 votes
3 answers
391 views
A triangle cannot be dissected into fewer than 9 convex pentagons. Is there a simple proof of this claim?
I want to dissect a triangle into $n$ strictly convex pentagonal pieces. This is possible with $n=9$: (One construction of the above arrangement is to remove a single vertex from the dodecahedral ...
0 votes
0 answers
65 views
Area Conservation in Geometric Dissections for Pythagorean Theorem Visualizations
I am an elementary school teacher in South Korea with a strong interest in developing intuitive, visual methods for teaching fundamental geometric concepts—especially the Pythagorean Theorem. I have ...
7 votes
1 answer
317 views
Generalized Pythagorean Dissection Tiling Result
I would sincerely appreciate any critical feedback or evaluation on the following result. Here's the context. Many of you are probably familiar with dissection proofs of the Pythagorean Theorem, such ...
1 vote
2 answers
101 views
How to partition a polygon into contiguous regions with given area ratios?
I am looking for a way to divide a 2D polygon (possibly with a complex shape, like an "H". These are actually floor layouts of buildings) into several connected sub-regions, where each ...
4 votes
2 answers
134 views
Can a cylinder be split in such a way that it can be reassembled into 3 equal cones?
I just saw this question on the HNQ, and it made me wonder. Is there any way that you could divide a cylinder into a finite number of pieces such that the pieces could be reassembled into three ...
3 votes
1 answer
126 views
Proof verification: A cube and a tetrahedron are not scissors congruent?
I am familiar with a proof that the cube and tetrahedron are not scissors congruent along the following lines: Given a polyhedron or collection of polyhedra $\mathcal{P}$ whose edges form a set $E$, ...
9 votes
1 answer
490 views
Can a dodecagon be cut into $n$ congruent pieces for any $n$ not of the form $1,2,3,4,6,8,12k^2,24k^2$?
Suppose I want to cut a regular dodecagon into $n$ congruent simply-connected pieces. For which $n$ is this possible? I can cut it into 24 right triangles, by cutting from the center to each vertex ...
4 votes
0 answers
122 views
Can $n$ squares each be dissected into identical polygons and then re-assembled into a a single larger square
Suppose you have $n$ unit squares. Can you dissect each square into polygons such that all the polygons are identical, and then re-arrange the polygons into a single big square of area $n$? Rotations, ...
16 votes
2 answers
1k views
Union of two disjoint congruent polygons is centrally symmetric. Must the polygons differ by a 180 degree rotation?
Let $P$ be a polygon with $180^\circ$ rotational symmetry. Let $O$ be the center of $P$ and suppose $P$ is dissected into congruent polygons $A$ and $B$. Must the $180^\circ$ rotation around $O$ ...
5 votes
3 answers
579 views
Square to octagon dissection - how to cut the square?
How to cut the square which tessellates to octagon using straightedge and compass? What are the exact measures of colored sides? What is the angle marked with red color? Edit (I added vertices): Edit....
4 votes
0 answers
326 views
Hexagon to Rectangle dissection: 3 pieces minimal?
A hexagon can be divided into 3 pieces to make a rectangle. Can we prove 3 pieces is minimal? For a equilateral triangle to square dissection, it's thought that 4 pieces is minimal. We can prove that ...
0 votes
0 answers
58 views
Does this kind of partition have a name?
Note: Reposting from OR Stackexchange as advised there. Consider a convex polyhedron $A$. Assume we have subsets $A_1,\ldots,A_n$ of $A$ that are themselves covex polyhedra and are mutually disjoint ...
-2 votes
1 answer
86 views
Is it always possible to cut out a piece of the triangle with $\frac{1}{3}$ the area?
This is a part $3$ of a sequence of questions starting with my highly upvoted question (at the time of writing, my third-best post). Feel free to extend this series using other polygons and fractions. ...
3 votes
2 answers
189 views
Is it always possible to cut out a piece of the triangle with half the area?
This is a sequel to my highly upvoted question (at the time of writing, my third-best post). Let there be an equilateral triangle that has $n+1$ notches on each edge (corners included) to divide each ...