Decahedron: Definitions and Examples

Decahedron: Definitions, Formulas, & Examples

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    Introduction:

    A decahedron is a solid geometric shape that has ten faces. The term “decahedron” comes from the Greek word “deka,” meaning ten, and “hedron,” meaning face. The decahedron is a polyhedron, which is a three-dimensional shape with flat faces and straight edges. In this article, we will explore the properties of a decahedron, different types of decahedra, and their applications.

    Definitions:

    Before we delve into the different types of decahedra, it’s essential to understand some basic terminology related to polyhedra.

    Vertex: The point where two or more edges meet.

    Edge: The line segment where two faces of a polyhedron meet.

    Face: A flat surface that forms a part of a polyhedron.

    Polyhedron: A three-dimensional shape with flat faces and straight edges.

    Regular decahedron: A decahedron with ten regular, congruent faces. All the angles and edges of a regular decahedron are equal.

    Irregular decahedron: A decahedron that does not have regular faces.

    Types of Decahedra:

    There are several types of decahedra, each with its unique set of properties. Here are five examples of decahedra:

    • Regular Decahedron:

    A regular decahedron is a Platonic solid with ten regular faces. All the faces of a regular decahedron are congruent and are regular pentagons. Each vertex of a regular decahedron is equidistant from the center of the polyhedron, making it a highly symmetrical shape. The regular decahedron has 20 vertices, 30 edges, and 10 faces. The regular decahedron is a popular shape in architecture, design, and jewelry making.

    • Trapezoidal Decahedron:

    A trapezoidal decahedron is an irregular decahedron with ten trapezoidal faces. The trapezoidal decahedron has 20 vertices, 30 edges, and 10 faces. The trapezoidal decahedron is often used in engineering and physics to study crystal structures.

    • Pentagon-Pentagon Decahedron:

    The Pentagon-Pentagon Decahedron is an irregular decahedron with ten pentagonal faces. Each of the ten faces is a regular pentagon, and each vertex has three faces meeting at it. The Pentagon-Pentagon Decahedron has 20 vertices, 30 edges, and 10 faces.

    • Hexagonal Bipyramidal Decahedron:

    The Hexagonal Bipyramidal Decahedron is an irregular decahedron with ten faces. It has two hexagonal faces, one at the top and one at the bottom, and eight trapezoidal faces in the middle. The Hexagonal Bipyramidal Decahedron has 20 vertices, 30 edges, and 10 faces.

    • Concave Decahedron:

    A concave decahedron is an irregular decahedron with ten faces. The concave decahedron has five concave and five convex pentagonal faces. The concave decahedron has 20 vertices, 30 edges, and 10 faces. Concave decahedra are used in mathematical models and computer graphics.

    Applications:

    The decahedron is a versatile shape used in a wide range of applications. Here are some examples of how decahedra are used in various fields:

    • Architecture:

    Decahedra are used in architecture for their aesthetic appeal and geometric properties. Architects use decahedra to create unique and visually striking designs for buildings, bridges, and other structures.

    Chemistry:

    Decahedra are used in chemistry to study crystal structures. The trapezoidal decahedron, in particular, is commonly used to study molecular arrangements in crystals.

    Mathematics:

    Decahedra are used in mathematics for their symmetrical properties and to explore geometrical relationships. The regular decahedron is a popular subject of study in mathematics due to its high degree of symmetry.

    Jewelry Making:

    Decahedra are used in jewelry making for their intricate and beautiful designs. The regular decahedron, in particular, is a popular choice for creating earrings, pendants, and other jewelry items.

    Conclusion:

    In conclusion, the decahedron is a fascinating shape with ten faces that has a wide range of applications in various fields. There are several types of decahedra, each with its unique set of properties, and they are used in architecture, chemistry, mathematics, and jewelry making. Whether you’re a mathematician, architect, jeweler, or scientist, the decahedron is a shape that offers endless possibilities for exploration and creativity.

    Quiz

    What is a decahedron?

    A: A decahedron is a solid geometric shape with ten faces.

    What is the origin of the term “decahedron”?

    A: The term “decahedron” comes from the Greek word “deka,” meaning ten, and “hedron,” meaning face.

    What is a polyhedron?

    A: A polyhedron is a three-dimensional shape with flat faces and straight edges.

    What is a regular decahedron?

    A: A regular decahedron is a decahedron with ten regular, congruent faces. All the angles and edges of a regular decahedron are equal.

    What is an irregular decahedron?

    A: An irregular decahedron is a decahedron that does not have regular faces.

    What is a trapezoidal decahedron?

    A: A trapezoidal decahedron is an irregular decahedron with ten trapezoidal faces.

    What is a pentagon-pentagon decahedron?

    A: A Pentagon-Pentagon Decahedron is an irregular decahedron with ten pentagonal faces.

    What is a hexagonal bipyramidal decahedron?

    A: A Hexagonal Bipyramidal Decahedron is an irregular decahedron with two hexagonal faces, one at the top and one at the bottom, and eight trapezoidal faces in the middle.

     

    What are some applications of decahedra?

    A: Decahedra are used in architecture, chemistry, mathematics, and jewelry making.

    Why is the regular decahedron a popular subject of study in mathematics?

    A: The regular decahedron is a popular subject of study in mathematics due to its high degree of symmetry.

     

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    Decahedron:

    Polyhedra with available data

    equilateral square antiprism | augmented pentagonal prism | augmented tridiminished icosahedron | equilateral pentagonal dipyramid | equilateral octagonal prism | square cupola (total: 6)

    Visual representations

    Visual representations

    Alternate names
    Combinatorial properties

     | vertices | edges | faces
equilateral square antiprism | 8 | 16 | 10 (8 triangles, 2 quadrilaterals)
augmented pentagonal prism | 11 | 19 | 10 (4 triangles, 4 quadrilaterals, 2 pentagons)
augmented tridiminished icosahedron | 10 | 18 | 10 (7 triangles, 3 pentagons)
equilateral pentagonal dipyramid | 7 | 15 | 10 (10 triangles)
equilateral octagonal prism | 16 | 24 | 10 (8 quadrilaterals, 2 octagons)
square cupola | 12 | 20 | 10 (4 triangles, 5 quadrilaterals, 1 octagon)

    Edge lengths

    1 (16 edges)

    1 (19 edges)

    1 (18 edges)

    1 (15 edges)

    1 (24 edges)

    1 (20 edges)

    Geometric properties

     | volume
equilateral square antiprism | ((2 - 1/(1 + 1/sqrt(2)))^(3/2) cot(Ï€/8))/(3 sqrt(2))
augmented pentagonal prism | 1/12 sqrt(233 + 90 sqrt(5) + 12 sqrt(50 + 20 sqrt(5)))
augmented tridiminished icosahedron | 1/24 (15 + 2 sqrt(2) + 7 sqrt(5))
equilateral pentagonal dipyramid | 1/12 (5 + sqrt(5))
equilateral octagonal prism | 2 (1 + sqrt(2))
square cupola | 1 + (2 sqrt(2))/3
 | surface area
equilateral square antiprism | 2 (1 + sqrt(3))
augmented pentagonal prism | 1/2 (8 + sqrt(37 + 10 sqrt(5) + 4 sqrt(75 + 30 sqrt(5))))
augmented tridiminished icosahedron | 1/2 sqrt(3/2 (62 + 15 sqrt(5) + 7 sqrt(75 + 30 sqrt(5))))
equilateral pentagonal dipyramid | (5 sqrt(3))/2
equilateral octagonal prism | 4 (3 + sqrt(2))
square cupola | 7 + 2 sqrt(2) + sqrt(3)
 | circumradius
equilateral square antiprism | 1/4 sqrt(4 + csc^2(Ï€/8))
equilateral octagonal prism | sqrt(5/4 + 1/sqrt(2))
square cupola | 1/2 sqrt(5 + 2 sqrt(2))
 | midradius
equilateral square antiprism | 1/4 csc(Ï€/8)
(assuming unit edge lengths)

    Nets

    Nets

    Skeleton graphs

     | skeleton graph name
equilateral square antiprism | 4-antiprism graph
augmented pentagonal prism | Johnson solid skeleton 52
augmented tridiminished icosahedron | Johnson solid skeleton 64
equilateral pentagonal dipyramid | 5-dipyramidal graph
equilateral octagonal prism | 8-prism graph
square cupola | Johnson solid skeleton 4

    Dual polyhedra

     | dual name
equilateral square antiprism | canonical 4-trapezohedron
equilateral pentagonal dipyramid | equilateral pentagonal prism

    Dual skeleton graphs

     | dual skeleton name
equilateral 4-antiprism | 4-trapezohedral graph
augmented pentagonal prism | (not a named graph)
augmented tridiminished icosahedron | (not a named graph)
equilateral pentagonal dipyramid | 5-prism graph
equilateral octagonal prism | 8-dipyramidal graph

    Common properties

    amphichiral | convex | equilateral | rigid | simple

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