Talk:Plane (geometry)/Archive 1: Difference between revisions
imported>Peter Schmitt (→Picture: new section) |
imported>Boris Tsirelson (→Remarks: new section) |
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Sorry, again. But this is even more a bad idea! This picture may -- perhaps! -- be used to illustrate the topological concept of a surface, | Sorry, again. But this is even more a bad idea! This picture may -- perhaps! -- be used to illustrate the topological concept of a surface, | ||
certainly not that of a plane. --[[User:Peter Schmitt|Peter Schmitt]] 00:42, 18 March 2010 (UTC) | certainly not that of a plane. --[[User:Peter Schmitt|Peter Schmitt]] 00:42, 18 March 2010 (UTC) | ||
== Remarks == | |||
"A plane is a surface on which a line perpendicular to a line which lies on that surface also falls entirely on the surface" — where is it taken from?? Hopelessly bad "definition". | |||
"A plane is made up of an infinite number of straight lines" — it surely contains infinitely many straight lines, as well as infinitely many triangles, circles etc. But is it "made up" of them?? | |||
"Surfaces can be parallel" — really? what is the definition of this notion? | |||
"Thus the surface has on it point A, point B, and point C is called surface ABC" — a plane is determined by three points (if not on a straight line), but a surface is not. | |||
"If this crumpled picture of the Earth was spread flat on a perfectly flat table, and the picture had absolutely no thickness, then it would be a plane" — no, it would be a finite domain on a plane. | |||
[[User:Boris Tsirelson|Boris Tsirelson]] 15:29, 28 March 2010 (UTC) | |||
Revision as of 09:29, 28 March 2010
Picture
Sorry, again. But this is even more a bad idea! This picture may -- perhaps! -- be used to illustrate the topological concept of a surface, certainly not that of a plane. --Peter Schmitt 00:42, 18 March 2010 (UTC)
Remarks
"A plane is a surface on which a line perpendicular to a line which lies on that surface also falls entirely on the surface" — where is it taken from?? Hopelessly bad "definition".
"A plane is made up of an infinite number of straight lines" — it surely contains infinitely many straight lines, as well as infinitely many triangles, circles etc. But is it "made up" of them??
"Surfaces can be parallel" — really? what is the definition of this notion?
"Thus the surface has on it point A, point B, and point C is called surface ABC" — a plane is determined by three points (if not on a straight line), but a surface is not.
"If this crumpled picture of the Earth was spread flat on a perfectly flat table, and the picture had absolutely no thickness, then it would be a plane" — no, it would be a finite domain on a plane.
Boris Tsirelson 15:29, 28 March 2010 (UTC)