Are the given lines in R^3 concurrent or parallel?

In summary, the conversation discusses questions about determining if three planes intersect at a single point and finding the point of intersection and distance between three lines in R^3. The first question suggests using a "test" with rationale to determine if the planes intersect at a single point without solving the system. The second question asks if all three lines can be concurrent, how to determine the point of intersection between two lines, and how to use this information to find the distance between two other lines. The conversation also mentions using direction vectors to determine if lines are parallel.
  • #1
rickster1
2
0

Homework Statement



Ok I have a bunch of questions, please bare with me and i'd appreciate it VERY much if you could help me with these!

1. Assume that you are given the equations of three planes. Without solving the system, describe a "test" with rationale, that you could use to determine whether or not the planes intersect at a single point.

2. Given the equations of three lines in R^3

L1 = (1,4,1) + t(3,3,-2)
L2 = (-3,-5,8) + r(5,0,1)
L3 = (3,-5,8) + s(-5,0,-1)

a) Can all three lines be concurrent (i.e interesect at one point)? Algebraic solution not required

b) Determine the point of intersection of L1 and L2

c) Use information of part a) to help in determining the distance between L3 and L2


End questions.


I'd appreciate it a lot if someone can help me... :(

Homework Equations



I'm not sure, I got these questions on a whim and my textbook doesn't offer much help other than simple formulas.

The Attempt at a Solution



I'm really unsure how to approach these questions.. I got them on a whim and I haven't faced this unit of calculus before..
 
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  • #2
Can you make more of an attempt at the questions? It's better you show us what you think instead of us just telling you the answers.

I'll get you started.

For 2a) a good place to start would be to determine whether any of the lines are parallel or not. After all, if they are parallel to one another, surely they won't intersect!

HINT: Look at the direction vectors of the each line.
 

1. What is the difference between a plane and a line in 3D?

A plane is a 2-dimensional surface that extends infinitely in all directions, while a line is a 1-dimensional object that extends infinitely in two opposite directions. In 3D, a plane is defined by three points, while a line is defined by two points.

2. How do you calculate the distance between a point and a plane in 3D?

The distance between a point and a plane in 3D can be calculated using the formula d = |ax + by + cz + d| / √(a^2 + b^2 + c^2), where (a,b,c) is the vector normal to the plane and (x,y,z) is the coordinates of the point.

3. Can a line and a plane intersect in 3D?

Yes, a line and a plane can intersect in 3D. The intersection point will be the solution to the system of equations formed by the line and the plane's equations.

4. How many points are needed to uniquely define a plane in 3D?

Three non-collinear points are needed to uniquely define a plane in 3D. If the points are collinear, then the plane is undefined.

5. Can a line and a plane be parallel in 3D?

Yes, a line and a plane can be parallel in 3D. This means that they do not intersect and have no common points. In this case, the line is perpendicular to the plane's normal vector.

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