Finding vectors parallel and perpendicular to plane

In summary, the conversation discusses finding a vector perpendicular to a given plane and a vector parallel to the plane. One participant suggests using the cross product of two perpendicular vectors, while another suggests finding two points on the plane to construct a vector parallel to it.
  • #1
1MileCrash
1,342
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Homework Statement



Find a vector perpendicular to plane z = 5 + 3x - y, and find a vector parallel to the plane.

Homework Equations





The Attempt at a Solution



The normal vector is simple, because my book addresses it. It is 3i - j - k.

I have absolutely no clue how to get a parallel vector to the plane. Any hints?
 
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  • #2
I've been thinking about this one for a bit. If you had another vector perp to the plane you could use a cross product. Also, you might have more luck on the calculus page.
 
  • #3
I've been getting really frustrated over this one. My only way of solving is that I know that the parallel vector is perpendicular to the normal vector, so therefore the dot product of those two vectors is 0, but that gives me infinite possibilities for the parallel vector... and there is a specific one the homework wants. Makes no sense to me at all.
 
  • #4
A cross product of two vectors perpendicular to the plane will give you a vector parallel to the plane.
 
  • #5
Froster78 said:
A cross product of two vectors perpendicular to the plane will give you a vector parallel to the plane.

And where do I get this second perpendicular vector?
 
  • #6
Ok, I think I have a better idea... Sorry I'm really using this to help myself as well. If you find two points, say (0,0,0) and (1,1,1) just using arbitrary points on your plane. You can construct a vector using the initial and terminal points. This vector should be parallel to the plane. You could obviously check this by the dot product with the normal vector.

does that help?
 

1. How do I determine if a vector is parallel to a plane?

To determine if a vector is parallel to a plane, you can use the dot product method. Take the dot product of the vector and the normal vector of the plane. If the result is 0, then the vector is parallel to the plane.

2. Can a vector be parallel and perpendicular to a plane at the same time?

No, a vector cannot be both parallel and perpendicular to a plane at the same time. A vector is parallel to a plane if its dot product with the normal vector of the plane is 0, while a vector is perpendicular to a plane if its dot product is nonzero.

3. How can I find a vector that is perpendicular to a given plane?

To find a vector that is perpendicular to a given plane, you can take the cross product of any two non-parallel vectors on the plane. The resulting vector will be perpendicular to both of these vectors and therefore perpendicular to the plane.

4. What is the significance of finding vectors parallel and perpendicular to a plane?

Finding vectors parallel and perpendicular to a plane is important in many fields of science, such as physics and engineering. It allows us to better understand the orientation and relationships between objects in 3-dimensional space.

5. Can a vector be parallel to one plane and perpendicular to another plane?

Yes, it is possible for a vector to be parallel to one plane and perpendicular to another plane. This can occur if the two planes are not parallel to each other. In this case, the vector will lie in the intersection of the two planes and will be parallel to one while perpendicular to the other.

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