What's it called when a 3D shape can be made of 2D surfaces of all the same size

In summary, the conversation discusses the concept of creating a 3D shape using 2D surfaces of the same shape and dimensions. It is mentioned that this can be done with certain equilateral shapes, such as triangles, squares, and pentagons. However, as the number of sides increases, it becomes impossible to create a 3D shape using only 2D surfaces of the same shape and dimensions. The conversation also raises the question of whether there are other shapes, both convex and concave, that can be used to create a 3D shape in the same way. The conversation ends with mentioning the Euler Formula as a way to determine the number of possible shapes that can be used to create a 3D shape.
  • #1
keysle
4
0
What's it called when a 3D shape can be made of 2D surfaces of all the same shape and dimensions?

To make a cube, I can use 6 4-sided-squares (of course they're 4 sided)
To make a pyramid (3 sided), I can use 4 3-sided-triangles

I can do this with pentagon as well (i don't know what the shape is called)

Eventually I can't do this as the sides of the shape increase because the remaining angle.


... after some thinking I realized I can only do this with 3 equilateral shapes.
3 sided
4 sided
and 5 sided

MRtiO.png


Once I get to the hexagon ... well

r6zJy.png




Now here's an even more interesting question: Are there any others shapes convex or concave equilateral or not that can be used to create a 3D shape? (where the base shapes remains the same)
If so how can one determine if a shape is capable of doing this?
 
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  • #2
Regular polyhedron
 
  • #3
Thanks!

Doesn't look like there are too many of those shapes.

Do you know about the second questions?
Now here's an even more interesting question: Are there any others shapes convex or concave equilateral or not that can be used to create a 3D shape? (where the base shapes remains the same)
If so how can one determine if a shape is capable of doing this?
 
  • #4
keysle said:
What's it called when a 3D shape can be made of 2D surfaces of all the same shape and dimensions?

To make a cube, I can use 6 4-sided-squares (of course they're 4 sided)
To make a pyramid (3 sided), I can use 4 3-sided-triangles

I can do this with pentagon as well (i don't know what the shape is called)

Eventually I can't do this as the sides of the shape increase because the remaining angle.


... after some thinking I realized I can only do this with 3 equilateral shapes.
3 sided
4 sided
and 5 sided

MRtiO.png


Once I get to the hexagon ... well

r6zJy.png




Now here's an even more interesting question: Are there any others shapes convex or concave equilateral or not that can be used to create a 3D shape? (where the base shapes remains the same)
If so how can one determine if a shape is capable of doing this?

You can use the Euler Formula to prove, if I remember correctly, there are only five which are all regular polygons. 4,6,8,12,20
 
  • #5


The term for a 3D shape that can be made of 2D surfaces of all the same size is known as a "uniform polyhedron" or "Platonic solid." This includes shapes such as the cube, pyramid, and dodecahedron.

The term for a 3D shape that can be made of 2D surfaces of all the same shape and dimensions is known as a "regular polyhedron." This includes shapes such as the cube and octahedron.

To determine if a shape is capable of being used to create a 3D shape with all surfaces of the same size or shape, one must examine the angles and sides of the shape. The only shapes that can be used in this manner are those with equilateral sides and angles. This is because the angles must fit together perfectly in order to create a solid 3D shape without gaps or overlaps. Therefore, the shape must have a certain level of symmetry and regularity in its sides and angles to be able to form a uniform or regular polyhedron.
 

1. What is the name of a 3D shape made of 2D surfaces of equal size?

The name of this type of 3D shape is a polyhedron.

2. Are all polyhedrons made of 2D surfaces of equal size?

No, not all polyhedrons are made of 2D surfaces of equal size. There are some polyhedrons, such as pyramids or cones, that have a combination of both 2D surfaces of equal size and curved surfaces.

3. What is the difference between a polyhedron and a polygon?

A polygon is a 2D shape with straight sides, while a polyhedron is a 3D shape made up of polygons. In other words, a polyhedron is a 3D version of a polygon.

4. Can a polyhedron have an infinite number of 2D surfaces of equal size?

No, a polyhedron can only have a finite number of 2D surfaces of equal size. This is because a polyhedron is a solid object and therefore cannot have an infinite number of surfaces.

5. What are some examples of polyhedrons?

Some examples of polyhedrons include cubes, prisms, tetrahedrons, octahedrons, and dodecahedrons. These shapes are commonly used in geometry and can be found in many everyday objects such as dice, packaging boxes, and buildings.

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