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2007-01-09 10:24:01 · 3 answers · asked by Zerro 2 in Science & Mathematics Mathematics

3 answers

If you had just one cube (1 x 1 x 1), there would be 6 external faces and 0 internal faces.

If you had eight SMALLER cubes (2 x 2 x 2), there would be 4 external faces on each side of the BIGGER cube, so 6 x 4 = 24 external faces. Each SMALLER cube has 6 faces, and there are 8 cubes, so there are 48 faces total. 48 total faces - 24 external faces = 24 internal faces.

If you had 27 SMALLER cubes (3 x 3 x 3), there would be 9 external faces on each side of the BIGGER cube, so 6 x 9 = 54 external faces. Each SMALLER cube has 6 faces, and there are 27 cubes, so there are 162 faces total. 162 total faces - 54 external faces = 108 internal faces.

Do you see the pattern?

If n is the number of cubes along a single edge of the BIGGER cube, then each BIGGER cube is composed of n × n × n = n³ cubes. On each side of the BIGGER cube, you would have n × n = n² external faces. Every BIGGER cube has 6 sides, so you would have 6n² external faces.

But you have n³ SMALLER cubes, and each of THEM has a total of 6 faces, for an overall total of 6n³ faces. So the number of internal faces is:

# of total faces - # of external faces = # of internal faces

6n³ - 6n² = 6n²(n - 1)

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There's a very good article on this topic on the mathforum website.

http://mathforum.org/library/drmath/view/56799.html

2007-01-11 01:31:52 · answer #1 · answered by Jim Burnell 6 · 0 0

well, if by, "hidden faces of a cube" you mean, the surfaces..then it is 6 on a cube. they will all have the same dimensions as the side facing you. cubes have six sides: 1 top, 1 bottom, 2 sides, one front and one back = 6 sides, all the same size & shape.

2007-01-09 18:28:36 · answer #2 · answered by Rob 2 · 0 0

All 6 faces of a cube are equal. So you do any one face and you are done.

2007-01-09 18:29:05 · answer #3 · answered by Sheen 4 · 0 0

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