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What is a 3faced 3D object? 
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#1
Jan1308, 09:21 AM

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Is there a 3D object with 3 faces? What is it called?



#2
Jan1308, 09:32 AM

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My mind cant comprehend the existence of such a shape



#3
Jan1308, 09:39 AM

P: 116

Thats like asking for a 2 sided 2D object.



#4
Jan1308, 09:40 AM

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What is a 3faced 3D object?
A politician?



#5
Jan1308, 04:31 PM

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A cylinder? Or must the faces be flat..?



#6
Jan1308, 05:17 PM

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No such object exists with flat sides.



#7
Jan1308, 05:23 PM

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three lines can only intersect in one point, coincide or be parallel so yes, no such object exists.



#8
Jan1308, 08:01 PM

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There is an infinite number of 3 dimensional objects with 3 faces, just as there are an infinite number 2 dimensional objects with 2 sides.



#9
Jan1308, 09:54 PM

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A tetrahedron with its base removed?



#10
Jan1308, 09:58 PM

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#11
Jan1308, 10:30 PM

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#12
Jan1308, 10:42 PM

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I think it's best we first clarify what a closed 3 dimensional object is for our purposes. I would say that a simple closed 3 dimensional object is a collection of planar surfaces with properties among which is that a surface in that collection connects to at least as many surfaces as it has vertices. The simplest planar figure is the triangle; since it has 3 sides, it is not possible to meet the said property with only 3 planar faces, hence there is no such 3 dimensional object.



#13
Jan1308, 11:07 PM

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#14
Jan1408, 12:47 AM

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#15
Jan1608, 08:36 PM

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What you are thinking of is a 3 dimensional (convex) polytope. I assume you mean codimension 1 faces (i.e. 2 dimensional faces). Technically, edges and vertices are also called faces. In this case, the minimum number of faces is 4 (a tetrahedron). In general, an n dimensional polytope needs to have at least n+1 facets. 


#16
Jan1708, 11:55 AM

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#17
Jan1708, 12:38 PM

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Wouldn't a Mobius strip have 3 faces? ie. 1 'face' and 2 edges.



#18
Jan1708, 02:22 PM

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But obviously no flat surfaced object could have 3 faces. (politicians aside) 


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