Finding three planes which intersect a point with lines

In summary, the problem requires finding three planes that intersect at the point (1,1,1) and each contain one of the three given lines. This can be done by setting up a system of equations using the given line equations and the dot product between the plane normals and line vectors. There may be multiple solutions for the planes, and the planes can be described using one vector and one point.
  • #1
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Homework Statement



The three lines intersect in the point (1; 1; 1): (1 - t; 1 + 2*t; 1 + t), (u; 2*u - 1; 3*u - 2), and (v - 1; 2*v - 3; 3 - v). How can I find three planes which also intersect in the point (1; 1; 1) such that each plane contains one and only one of the three lines?

Homework Equations



plane aix + biy + ciz = di

The Attempt at a Solution

I get 9 equations:

Sharing equations with the lines:

a1(1 - t) + b1(1 + 2*t) + c1(1 + t) = d1
a2(u) + b2(2*u - 1) + c2(3*u - 2) = d2
a3(v - 1) + b3(2*v - 3) + c3(3 - v) = d3

Intersection at (1,1,1):

a1 + b1 + c1 = d1
a2 + b2 + c2 = d2
a3 + b3 + c3 = d3

Dot product of plane normals and line vectors = 0 since perpendicular:

<a1; b1; c1> dot <-1; 2; 1> = -a1 + 2*b1 + c1 = 0
<a2; b2; c2> dot <1; 2; 3> = a2 + 2*b2 + 3*c2 = 0
<a3; b3; c3> dot <1; 2; -1> = a3 + 2*b3 - c3 = 0

I know how to find the intersection of 3 planes using matrices/row reduction, and I know some relationships between lines and planes. However, I seem to come up with 12 unknowns and 9 equations for this problem. I know the vectors for the lines must be perpendicular to the normals of the planes, thus the dot product between the two should be 0. I also know that the planes pass through the point (1,1,1) and the x,y,z coordinates for the parameters given in the line equations. What information am I missing? Maybe there are multiple solutions. If so, how can these planes be described with only a line and one point? Another thought was to convert the planes to parametric form, but to describe a plane with parameters normally I would have 2 vectors and one point, but here I only have one vector and one point.
 
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  • #2
this can be closed as I slept on it and figured it out...

once you know the vectors you can find the planes since there are multiple answers you can choose values of a,b,c as long as they satisfy the perpendicular equation and going through the point 1,1,1.
 

Related to Finding three planes which intersect a point with lines

1. How do you find three planes that intersect at a point?

The process of finding three planes that intersect at a point involves solving a system of equations. Each plane can be represented by an equation in the form of ax + by + cz = d, where a, b, and c are the coefficients of the variables and d is a constant. By setting up a system of three equations with three variables, you can solve for the coordinates of the point where the three planes intersect.

2. What is the significance of three planes intersecting at a point?

When three planes intersect at a point, it means that there is a single coordinate that satisfies all three equations. This can be thought of as the point where the three planes converge or intersect in three-dimensional space.

3. Can three planes intersect at more than one point?

No, in three-dimensional space, three planes can only intersect at one point. This is because a point is defined by its unique set of coordinates, and the three planes can only have one common set of coordinates where they intersect.

4. What happens if the three planes are parallel?

If the three planes are parallel, they will not intersect at any point. This means that there is no solution to the system of equations, and the planes are said to be consistent and have no common point of intersection.

5. Are there any shortcuts or special methods for finding three planes that intersect at a point?

There are various methods and strategies for finding three planes that intersect at a point, such as using matrices or using geometric principles. However, the most common and reliable method is to solve a system of equations by substitution or elimination.

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