Calculating Distance Between a Line and a Plane

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Homework Help Overview

The problem involves calculating the shortest distance between a given plane and a line defined by two points in three-dimensional space. The subject area encompasses concepts from geometry and vector calculus.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to find the distance from a line to a plane, expressing familiarity with the distance from a point to a plane but uncertainty about extending that to a line. Participants discuss the normal vector to the plane and the direction vector of the line, considering the implications of their dot product.

Discussion Status

Participants are exploring the relationship between the line and the plane, with one noting that the line is parallel to the plane based on the dot product being zero. There is a suggestion that any point on the line can be used to determine the distance from the plane.

Contextual Notes

Participants mention that a line can either intersect a plane, be parallel to it, or lie within it, indicating that these scenarios should be tested to understand the relationship better.

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Homework Statement


Find the shortest distance between the plane 2x−6y+4z=10 and the line passing through the points (0,-15,8) and (-6,-13,14).

The Attempt at a Solution


So orthogonal vector to the plane is (2, -6, 4)T
The parametric equation of the line is:
L=(0,-15,8)+t(-3,1,3)

And I don't know after that. I can find distance from a point to a plane, but not from a line. Any help will be appreciated.
 
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If N is the normal vector to the plane which you've found to be (2,-6,4) and you found the direction of L to be u=(-3,1,3).

Consider what N.u works out to be and what it means.


EDIT: Forgot to put in that when it comes to a line and a plane, the line is will either intersect it at one point, is parallel to the plane or lies within the plane. Can easily test for all. Best to test for the second and third one when starting the question.
 
Last edited:
Well, the dot product is 0 meaning L is perpendicular to N, so it's parallel to the plane. So any point on L is equidistant from the plane. So I can just use (0, -15,8) to find the distance?

Neat, thanks!
 
yes, you should be able to.
 

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