Find perpendicular vector and plane through given point

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Homework Help Overview

The discussion revolves around finding the coefficients of a plane equation that is perpendicular to a given line and passes through a specific point in three-dimensional space. The line is defined parametrically, and the participants are tasked with determining the values of a, b, c, and d in the plane equation ax + by + cz = d.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between the line and the plane, noting that the direction vector of the line is crucial for determining the normal vector of the plane. There are attempts to clarify the relevance of the starting point of the line and how to find a vector that is perpendicular to the line's direction vector. Questions arise about the correct interpretation of the plane's equation and the use of the point through which the plane must pass.

Discussion Status

Some participants express confusion about the relationship between the line and the plane, while others clarify that the direction vector of the line serves as the normal vector for the plane. There is a recognition that the equation of the plane can be derived from this relationship, and guidance is provided on how to formulate the plane's equation using the known point.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information available or the methods they can use. There is an emphasis on understanding the geometric relationships involved rather than simply applying formulas.

theown1
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Homework Statement


Consider the line and plane below.
x = 5-5t, y = 3+7t, z = 10t
ax + by + cz = d

Find values of a, b, c, and d so that the plane is perpendicular to the line and through the point (2, 1, 2).

Homework Equations


Fgrad=(x',y',z') is perp to surface
if \vec{v}1\bullet\vec{v}2=0
then v1\botv2

The Attempt at a Solution



when I put those x,y,z values together I get a parametric equation that equals <5,3,0>+t<-5,7,10>

the starting point <5,3,0> I think is not relevant to finding a perpendicular vector,
I just need to find a vector perpendicular to t<-5,7,10> that goes through (2,1,2) i think? but I'm not sure how to do this..
then once I find the vector that's perp to t<-5,7,10>(dot)<a,b,c>=0
once I know a,b,c I can solve for d
 
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Consider the equation of the line:
(x,y,z) = (5,3,0) + t(-5,7,10)
Which is really just translated from:
(x,y,z) = t(-5,7,10)
Which is what you have so far.
So by definition the plane is defined by all vectors perpendicular to (-5,7,10)
Which is just 7y + 10z - 5x = 0
Translated plane:
v dot (x-x0) = 0
You complete.
 
theown1 said:

Homework Statement


Consider the line and plane below.
x = 5-5t, y = 3+7t, z = 10t
ax + by + cz = d

Find values of a, b, c, and d so that the plane is perpendicular to the line and through the point (2, 1, 2).

Homework Equations


Fgrad=(x',y',z') is perp to surface
if \vec{v}1\bullet\vec{v}2=0
then v1\botv2


The Attempt at a Solution



when I put those x,y,z values together I get a parametric equation that equals <5,3,0>+t<-5,7,10>

the starting point <5,3,0> I think is not relevant to finding a perpendicular vector,
I just need to find a vector perpendicular to t<-5,7,10> that goes through (2,1,2) i think?
No, you don't. You want to find a vector perpendicular to the plane in order to write the equation of the plane. Since the line itself is perpendicular to the plane, its "direction vector", <-5, 7, 10>, is perpendicular to the plane.
So you know the plane can be written as -5(x-x_0)+ 7(y-y_0)+ 10(z-z)= 0, where (x_0, y_0, z_0) is some point in the plane. Any you are also given that.&lt;br /&gt; &lt;br /&gt; &lt;blockquote data-attributes=&quot;&quot; data-quote=&quot;&quot; data-source=&quot;&quot; class=&quot;bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch&quot;&gt; &lt;div class=&quot;bbCodeBlock-content&quot;&gt; &lt;div class=&quot;bbCodeBlock-expandContent js-expandContent &quot;&gt; but I&amp;#039;m not sure how to do this..&lt;br /&gt; then once I find the vector that&amp;#039;s perp to t&amp;lt;-5,7,10&amp;gt;(dot)&amp;lt;a,b,c&amp;gt;=0&lt;br /&gt; once I know a,b,c I can solve for d &lt;/div&gt; &lt;/div&gt; &lt;/blockquote&gt;
 
Ok, ok I understand now

since the line is already perp. to the plane, the direction of the line corresponds to the gradient of the plane which is <a,b,c> and then i just use the equation of a plane to solve
d=a(x-xo)+b(y-yo)+c(z-zo)

thanks
 

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