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4_Legs_Good Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 01:52 PM
Original message
Geometry help... 3d rectangle
Hey!

I have Ph.D.'s here who don't know what a 3D rectangle is called. We're all stumped. Does anyone know for sure? So far the best we've come up with is "rectangular prisim".

Thanks!

david
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larryepke Donating Member (524 posts) Send PM | Profile | Ignore Tue Aug-05-03 01:53 PM
Response to Original message
1. rectangular prism
Edited on Tue Aug-05-03 01:55 PM by larryepke
is correct.

Here's an internet link on how to find the surface area of one.

http://www.aaamath.com/geo79-surface-area-rec-prism.html
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4_Legs_Good Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:01 PM
Response to Reply #1
6. Thanks!
Yeah, I think that's right. It just doesn't intuitively click.

Thanks again!

david
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GregW Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 01:55 PM
Response to Original message
2. Why not irregular hexahedron?
Given that a cube is a "regular hexahedron".
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larryepke Donating Member (524 posts) Send PM | Profile | Ignore Tue Aug-05-03 01:57 PM
Response to Reply #2
4. Well, for one thing...
if the angles aren't 90 degrees, the irregular hexahedron could be something other than a rectangular prism (think of a hammered dulcimer, for example).
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Occulus Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:01 PM
Response to Reply #4
7. Quick!
Edited on Tue Aug-05-03 02:01 PM by kgfnally
How do I find the surface area of an icosododecahedron?

:silly:
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Rabrrrrrr Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:22 PM
Response to Reply #7
12. You mean an Icosidodecahedron?
12 times the surface area of the pentagons plus 20 times the surface area of the traingles.

http://mathworld.wolfram.com/Icosidodecahedron.html
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PeteC Donating Member (74 posts) Send PM | Profile | Ignore Tue Aug-05-03 01:56 PM
Response to Original message
3. How about pyramid
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PeteC Donating Member (74 posts) Send PM | Profile | Ignore Tue Aug-05-03 01:57 PM
Response to Original message
5. sorry
was thinking triangle.
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Rabrrrrrr Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:03 PM
Response to Original message
8. parallelepiped
Edited on Tue Aug-05-03 02:09 PM by Rabrrrrrr
the term for a 6-sided rectanglular object with all right angles.

on edit: spelled the durn thing wrong
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ret5hd Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:13 PM
Response to Reply #8
10. where i'm from we call it a box. (nt)
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larryepke Donating Member (524 posts) Send PM | Profile | Ignore Tue Aug-05-03 02:16 PM
Response to Reply #8
11. maybe not
http://mathworld.wolfram.com/Parallelepiped.html

Since the sides of a parallelepiped only have to be parallelograms, you could still have an item with angles other than 90 degrees.
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Rabrrrrrr Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 02:24 PM
Response to Reply #11
13. oops - you're right!
Should be rectangular parallelepiped.

Thanks for the corrective!
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sigmaphinothing Donating Member (180 posts) Send PM | Profile | Ignore Tue Aug-05-03 02:04 PM
Response to Original message
9. tetrahedron
is the name of a platonic solid with 4 sides , each a equalateral triangle
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_NorCal_D_ Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Aug-05-03 03:06 PM
Response to Reply #9
14. Yes,
I think a 3-D triangle is a tetrahedron, as I recall.
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