Intersecting Planes: Visualizing & Explaining

  • Context: High School 
  • Thread starter Thread starter RoughRoad
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Discussion Overview

The discussion centers around the geometric concept of intersecting planes, specifically how two planes can intersect to form a line. Participants explore various ways to visualize this concept and provide explanations, models, and examples to aid understanding.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant states that a line is formed by the intersection of two planes and seeks help in visualizing this concept.
  • Another participant suggests creating physical models or drawings to better understand the intersection of planes.
  • There is a proposal that the intersection could be visualized as two squares intersecting along a common side.
  • A participant mentions looking at the corner of a room as an example of how walls (planes) intersect to form a line.
  • Another participant reiterates the corner of a room example, adding a humorous note about the OP's location.
  • One participant discusses how the size of the intersection depends on the ambient space, explaining different scenarios for intersections in three and four-dimensional spaces.
  • A participant questions the phrase "dies of a boc," suggesting it may have been intended to mean "sides of a box."
  • A later reply provides a practical visualization method using cardboard pieces with slits to represent the planes and their intersection.

Areas of Agreement / Disagreement

Participants generally agree on the concept that two planes can intersect to form a line, but there are varying methods and examples proposed for visualizing this intersection. Some participants provide different contexts and dimensions for the intersection, indicating a lack of consensus on the best way to visualize the concept.

Contextual Notes

Some statements depend on specific definitions of planes and intersections, and the discussion includes varying interpretations of dimensionality, particularly regarding intersections in three versus four-dimensional spaces.

RoughRoad
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I read somewhere that a line is formed as a result of intersection of two planes.

Now, I can't imagine it geometrically. Can someone help me visualise this? Or atleast explain me what it means?
 
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What you read is true. Why can you not visualize two planes intersecting? Make a physical model, or look for a physical model in the real world which fits this. The words can only take you to a limited extent; after that, you must think, and make drawings and try to build simple models.
 
Is it something like two squares intersecting, and both sharing a common side?
 
Paddle wheel?
 
Look at a corner of the room you are sitting in. The walls are planes and they intersect on the line forming the corner.
 
HallsofIvy said:
Look at a corner of the room you are sitting in. The walls are planes and they intersect on the line forming the corner.
I hope the OP isn't sitting in an igloo!:biggrin:
 
the size of the intersection of two objects depends also on the ambient space containing them. the bigger that space the more room they have to separate and the smaller is their intersection. So two planes in three space intersect either in a line l, like the dies of a boc meeting along an edge, or they coincide, thus intersecting in a plane, or they are parallel, and do not intersect at all, i.e. their intersection is empty.

but in 4 space, 2 planes can also intersect in a point. thus in linear algebra, two linear equations in 4 variables define a plane, so 4 equations define two planes and they can have a unique simultaneous solution.
 
[PLAIN]http://mathwise.net/pages/geometry/Glencoe_Geometry_Notes_and_Tests/chapter_1_geometry_notes_files/image008.gif
 
Last edited by a moderator:
mathwonk said:
So two planes in three space intersect either in a line l, like the dies of a boc meeting along an edge,...
dies of a boc - ?

Maybe you're saying "sides of a box"
 
  • #10
RoughRoad said:
I read somewhere that a line is formed as a result of intersection of two planes.

Now, I can't imagine it geometrically. Can someone help me visualise this? Or atleast explain me what it means?

To visualize it, take two pieces on carboard. Make a slit in each piece than connect the two pieces via the slits.

Each piece of carboard is a plane. The two planes meet at the slits. The intersection of the two planes is a straight line.
 
Last edited:

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