Finding The Distance From A Paraboloid To A Plane.

In summary: Maybe you missed something.In summary, the student is trying to solve for the vectors that are parallel to the paraboloid, but is having difficulty.
  • #1
Baumer8993
46
0

Homework Statement



Find the distance from the paraboloid z = X2 + 2Y2 to the plane
2X + 8Y + Z = -8.


Homework Equations



The partial derivatives with respect to X, And Y for the paraboloid.



The Attempt at a Solution



My professor said we need to find the point where the tangent plane of the paraboloid is parallel to the plane. I can take the X, and Y partial derivatives, but then I do not know what to do.
 
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  • #2
You should know what the normal vector to the plane is by looking at it. You want to find a point on the paraboloid whose normal vector is parallel to that. How would you find a normal vector to the surface at a point (x,y,z)?
 
  • #3
Oh I just need to move the Z over then take the gradient.
 
  • #4
Baumer8993 said:
Oh I just need to move the Z over then take the gradient.

Yes, and the simple way to check if two vectors are parallel is to see if one is a multiple of the other.
 
  • #5
Ok, so now I am stuck at the finding the vectors that are parallel. I know that they can be a multiple of each other. I got the gradient of < 2X, 4y, -1>. I know the normal vector is
<2, 8, 1>.

I set the equations to make:

2X = 2K 4Y = 8K -1 = 1K

K is just a constant. How do I solve these?
 
  • #6
Baumer8993 said:
Ok, so now I am stuck at the finding the vectors that are parallel. I know that they can be a multiple of each other. I got the gradient of < 2X, 4y, -1>. I know the normal vector is
<2, 8, 1>.

I set the equations to make:

2X = 2K 4Y = 8K -1 = 1K

K is just a constant. How do I solve these?

Good job setting the equations up, but I'm having a hard time figuring out why you can't solve -1=1*K. Take another look at them.
 
Last edited:

1. How do you find the distance from a paraboloid to a plane?

To find the distance from a paraboloid to a plane, you can use the formula d = |Ax + By + Cz + D| / √(A² + B² + C²), where A, B, and C are the coefficients of the plane's equation and D is the constant term.

2. What is a paraboloid?

A paraboloid is a three-dimensional surface that resembles a parabola in one direction and a circular arc in the other direction. It can be formed by rotating a parabola around its axis or by revolving a straight line around a fixed point.

3. What is a plane?

A plane is a two-dimensional surface that extends infinitely in all directions and is defined by three points or a point and a normal vector. It is a flat surface that does not curve or bend.

4. Why is it important to find the distance from a paraboloid to a plane?

Finding the distance from a paraboloid to a plane is important in various fields, such as engineering, physics, and mathematics. It can help determine the optimal distance between two objects, the trajectory of a projectile, or the intersection points of two surfaces.

5. Can the distance from a paraboloid to a plane be negative?

No, the distance from a paraboloid to a plane cannot be negative. It represents the shortest distance between the two surfaces, and distance is always a positive value. A negative value would indicate that the surfaces are intersecting or overlapping.

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