Find a plane given a point and a parallel line

In summary, the student is struggling to find the equation of a plane through a given point and parallel to a given line. They have a directional vector for the line but are unsure how to find the normal vector for the plane with only one directional vector. They question whether it is possible to find the normal vector through the dot product and if having only one point on the plane is enough information to find the equation. The student's professor has not provided any additional information or clarification on the question.
  • #1
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Homework Statement



Find the equation of the plane through the point (-2,8,10) and parallel to the line x= -2+t, y= 1+2t, z= 4-3t.

Homework Equations





The Attempt at a Solution



Now, I understand that I have to find the normal vector to the line (and the plane), but how can I do that if I only have one directional vector? If I had another directional vector, I could use the cross product.
I understand that the line has directional vector of (1,2,-3). Is there a way to get the normal vector through this information alone? Maybe by finding the orthogonal vector through the dot product or something (can you do that)?
If I have enough information to find the normal vector, would having only one point on the plane give me enough information to get the equation of the plane?

Thanks for your time, I'm having trouble here.
 
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  • #2
This is obviously not enough information, since I could easily draw two different planes going through a given point a parallel to a certain line (try it yourself).

Maybe they mean that the normal is parallel to the line? Then it is enough information of course...
 
  • #3
I'm not sure what he wants. This is a question on a practice test that the professor made up himself- the questions aren't out of any book or anything.
When I asked him about the question, I insisted that I needed another point or something, but he said that the information was all there and that's all that I got out of him.

The question shown is exactly how it's stated, though. Unless, like you said, it's just badly worded?
 
  • #4
Well, as I've said, I could draw a lot of planes parallel to the given line and passing through the point. I can only guess he meant the normal being parallel to the line. Otherwise send your prof here :-)
 

FAQ: Find a plane given a point and a parallel line

How do you find a plane given a point and a parallel line?

To find a plane given a point and a parallel line, you need to first identify the coordinates of the given point and the equation of the parallel line. Then, you can use the point-slope form of the equation of a plane to determine the equation of the plane. This equation will have three variables (x, y, and z) and can be written in standard form Ax + By + Cz + D = 0.

Can a plane be uniquely determined by a point and a parallel line?

No, a plane cannot be uniquely determined by a point and a parallel line. This is because there are infinite planes that can contain the given point and be parallel to the given line. The equation of a plane can only be determined if another condition, such as another point or a perpendicular line, is given.

What is the significance of a parallel line in finding a plane?

A parallel line is significant in finding a plane because it provides a direction for the plane. The equation of a parallel line can be used to determine the normal vector of the plane, which is a vector perpendicular to the plane. This normal vector is essential in determining the equation of the plane.

Can a plane be found if only a point and a perpendicular line are given?

Yes, a plane can be found if a point and a perpendicular line are given. In this case, the equation of the perpendicular line can be used to determine the normal vector of the plane. Then, the point-slope form of the equation of a plane can be used to determine the equation of the plane.

How many points are needed to uniquely determine a plane?

Three non-collinear points are needed to uniquely determine a plane. This is because three points can determine a unique plane and its corresponding equation. If only two points are given, there are infinite planes that can contain those points. If four or more points are given, they may not all lie in the same plane and therefore cannot uniquely determine a plane.

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