Talk:Prism (geometry)

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Mathematics rating:	Start Class	Mid Priority	Field: Geometry
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Please update this rating as the article progresses, or if the rating is inaccurate. Click to show/hide comments. Please add to or update the comments to suggest improvements to the article. Geometry guy 21:23, 9 July 2007 (UTC)

What consists of the base on a prism? Length times width?--STANG281 05:50, 7 November 2005 (UTC)

This passage, which i have rewrit, must reflect a failure of visual imagination by someone reconstructing what they had learned:

The rectangular prism, or cuboid, and square prism are among the types of right prism, with a rectangular and square base, respectively.

I say so for the following reasons:

• It is unmathematical to waste those prism terms on the cuboid and the square cuboid.
• A std. dictionary, in case of the analogous right circular cylinder, does not waste the name "circular cylinder" on it: if you make the proper parallel oblique cuts off the ends of a right elliptical cylinder, you get an oblique circular cylinder; the oblique and right circular cylinders together constitue the circular cylinders.

To imagine an oblique rectangular prism, picture two identical rigid rectangles, with eyes at the vertices; tie the eyes together in pairs with 4 equal-length inelastic strings. Hold one horizontal; the other will hang below it, also horizontal; that's your right rectangular prism. Have someone you trust nail down the bottom one, and keep all the strings taut. If you displace the top in any direction not parallel to a side, while keeping the strings taut, you have an oblique rectangular prism. Or, if you have trouble seeing that, move the top so that two edges stay in the same vertical plane they previously occupied, then (try to) move it perpendicular to that plane (it won't move a finite distance perpendicularly). In either case, the only right angles are on the top and bottom, and you have what must be called an oblique rectangular prism. The rectangular prisms must be the oblique rectangular prisms and the right rectangular prisms.
If i'm wrong, come up with a reliable reference that verifies the other supposed meaning. (If you do, the old article still needs work to clarify the illogical terminology.)
--Jerzy (t) 19:07, 2005 Apr 15 (UTC)