Geometry help... 3d rectangle

[4_Legs_Good]

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

[larryepke]

1. rectangular prism

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

[4_Legs_Good]

6. Thanks!

Yeah, I think that's right. It just doesn't intuitively click.

Thanks again!

david

[GregW]

2. Why not irregular hexahedron?

Given that a cube is a "regular hexahedron".

[larryepke]

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).

[Occulus]

7. Quick!

How do I find the surface area of an icosododecahedron?

:silly:

[Rabrrrrrr]

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

[PeteC]

3. How about pyramid

[PeteC]

5. sorry

was thinking triangle.

[Rabrrrrrr]

8. parallelepiped

the term for a 6-sided rectanglular object with all right angles.

on edit: spelled the durn thing wrong

[ret5hd]

10. where i'm from we call it a box. (nt)

[larryepke]

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.

[Rabrrrrrr]

13. oops - you're right!

Should be rectangular parallelepiped.

Thanks for the corrective!

[sigmaphinothing]

9. tetrahedron

is the name of a platonic solid with 4 sides , each a equalateral triangle

[_NorCal_D_]

14. Yes,

I think a 3-D triangle is a tetrahedron, as I recall.