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Hexagon

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In geometry, a hexagon is a polygon defined by having six sides and six corners, or vertices. The term originates from the Greek words for "six" and "corner."

Regular polygon 6 annotated
Regular polygon 6 annotated

For any simple hexagon that does not intersect itself, the sum of the internal angles is always 720 degrees. This mathematical property remains constant regardless of the specific lengths of the sides or the measures of individual angles. Understanding the hexagon is essential because it serves as a fundamental building block in both theoretical geometry and natural structures.

A regular hexagon is a specific type of hexagon that is both equilateral and equiangular. This means all six sides are the same length, and all six internal angles are equal. Each internal angle of a regular hexagon measures exactly 120 degrees, which is one-third of a full circle.

Regular hexagon 1
Regular hexagon 1

You can also construct a regular hexagon by taking an equilateral triangle and cutting off its three vertices. This shape is considered bicentric, meaning it possesses both a circumscribed circle and an inscribed circle. The circumscribed circle, or circumcircle, passes through all six vertices. The inscribed circle, or incircle, touches the midpoint of every side.

Regular polygon 12 annotated
Regular polygon 12 annotated

The internal geometry of a regular hexagon reveals fascinating relationships between its dimensions. If you place a point at the exact center and connect it to each vertex, you partition the hexagon into six equilateral triangles.

Hexagon dissection
Hexagon dissection

Because of this, the longest diagonals, which connect opposite vertices, are exactly twice the length of a single side. The maximal diameter, denoted as D, is equal to twice the circumradius, R, which is also equal to the side length, t. The minimal diameter, or the distance between parallel sides, is twice the inradius, r. These measurements allow mathematicians to calculate the area using the perimeter and the apothem, which is the radius of the inscribed circle.

Symmetry is a central concept when studying the regular hexagon. It possesses dihedral symmetry of order 12, often labeled as D6. This includes six rotational symmetries, where the shape looks identical after certain turns, and six reflection symmetries, which are lines where the shape can be folded perfectly.

Hexagon reflections
Hexagon reflections

These symmetries are organized into 16 subgroups, including various cyclic and dihedral groups. Mathematician John H. Conway helped categorize these complex patterns in his work on the symmetries of shapes.

Regular hexagon symmetries
Regular hexagon symmetries

Even when hexagons are not regular, they can still exhibit symmetry. For example, an isogonal hexagon might alternate between long and short edges, while an isotoxal hexagon might alternate between different internal angles.

One of the most significant properties of hexagons is their ability to tessellate, or tile, a flat plane. Like squares and equilateral triangles, regular hexagons can fit together without leaving any gaps. In a regular hexagonal tiling, exactly three hexagons meet at every vertex.

Isohedral tiling p6-1
Isohedral tiling p6-1

This efficiency is why bees use hexagons to build honeycombs. By using this shape, bees can fill a large area using the minimum amount of wax while maintaining great structural strength under compression. This makes the hexagon a master of space and material management in the natural world.

Hexagons also appear in complex mathematical dissections and higher-dimensional projections. A regular hexagon can be dissected into three rhombi, which are diamond-shaped parallelograms.

6-gon rhombic dissection2-size2
6-gon rhombic dissection2-size2

This decomposition is related to how a cube can be projected onto a two-dimensional surface. Furthermore, the hexagon appears in advanced algebra through the study of Lie groups. The roots of the simple Lie group A2 and the exceptional Lie group G2 are represented in patterns that follow hexagonal arrangements. These connections show that the hexagon is not just a simple shape, but a link between geometry, nature, and high-level mathematics.

Beyond flat surfaces, hexagons can exist in three-dimensional space as "skew" hexagons. A skew hexagon has vertices that do not all lie on the same flat plane, causing the edges to zig-zag through space.

Cube-skew-orthogonal-skew-frame
Cube-skew-orthogonal-skew-frame

A regular skew hexagon can be seen as the Petrie polygon for certain polyhedra, such as a cube or an octahedron. Whether they are flat tiles in a honeycomb or complex paths in a three-dimensional structure, hexagons provide a recurring pattern that defines much of the mathematical landscape.

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🖼️ Images & Media (84)
File:Regular hexagon 1.svg
Regular hexagon 1.svg
File:Hexagon reflections.svg
Hexagon reflections.svg
File:Regular hexagon symmetries.svg
Regular hexagon symmetries.svg
File:Isohedral_tiling_p6-13.svg
Isohedral_tiling_p6-13.svg
File:Isohedral_tiling_p6-12.svg
Isohedral_tiling_p6-12.svg
File:Isohedral_tiling_p6-7.svg
Isohedral_tiling_p6-7.svg
File:Isohedral tiling p6-11.svg
Isohedral tiling p6-11.svg
File:Isohedral tiling p6-10.svg
Isohedral tiling p6-10.svg
File:Isohedral tiling p6-9.svg
Isohedral tiling p6-9.svg
File:Isohedral tiling p6-1.svg
Isohedral tiling p6-1.svg
File:Root system A2.svg
Root system A2.svg
File:Root system G2.svg
Root system G2.svg

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