Are two vectors with opposite angles parallel to each other?

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Discussion Overview

The discussion centers on the concept of vector parallelism, specifically whether two vectors with opposite angles can be considered parallel. It explores definitions and implications of parallelism in the context of vector mathematics.

Discussion Character

  • Debate/contested
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • Some participants propose that vectors with opposite angles, such as \(\vec{A}=(3,-2)\) and \(\vec{B}=(-3,2)\), are considered "anti-parallel" rather than parallel.
  • Another participant clarifies that "parallel" for vectors differs from geometric parallelism, citing that vectors like <2, 1> and <6, 3> are parallel, while their corresponding lines are not.
  • A participant questions the requirement to provide coordinates for vector B, asking whether to include both the parallel and anti-parallel vectors.
  • Another participant points out that there are infinitely many vectors parallel to a given vector and asks for additional conditions regarding vector B.
  • One participant suggests that if vector E is parallel to vector F, it must maintain the same angle relative to the x-axis, leading to a system of equations to determine possible vectors.
  • There is a query about whether to provide only the parallel vector or both the parallel and anti-parallel vectors in the response.

Areas of Agreement / Disagreement

Participants express differing views on the definition of parallelism in vectors, with some agreeing on the term "anti-parallel" while others seek clarification on the requirements for providing vector coordinates. The discussion remains unresolved regarding the specific conditions for vector B.

Contextual Notes

Participants note the ambiguity in the original question and the lack of additional conditions for vector B, which affects the clarity of the discussion.

devanlevin
if two vectors, [tex]\vec{A}[/tex] and [tex]\vec{B}[/tex] have opposite angles, [tex]\vec{A}[/tex]=(3,-2) [tex]\vec{B}[/tex]=(-3,2) for example, are they considered parralel to each other even though they are in opposite directions
 
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They are "anti-parallel". "Parallel" for vectors is not quite the same thing as parallel for lines in geometry. For example, we would certainly say that the vectors <2, 1> and <6, 3> are parllel but the lines given by (2t, t) and (6t, 3t) are NOT "parallel". In fact, they are different representations of the same line.
 
in the question i am asking about i am told that vector A is parallel to vector B, and i am supposed to give coordinates of B, am i meant to give just the coordinates of the vector in the same direction or both that and the opposing direction??
 
The question doesn't make sense. There are an infinite number of vectors parallel to a given vector A. What other conditions are you given for B?
 
thats not really relevant, just wanted to know if i must give both vectors or just the 1
anyway
Vector E is parallel to Vector F, E=5cm F=(6,-7)
what are the values of E
 
If E is 5cm, then Sqrt[x^2+y^2] must equal 5cm. And if its parallel to F, it must have the same angle with respect to x-hat, that is ArcTan[y/x] must equal ArcTan[-7/6], which implies -7x = 6y. Two equations and two unknowns. You'll get two possible vectors, one parallel and one anti-parallel.
 
Last edited:
Skatch said:
You'll get two possible vectors, one parallel and one anti-parallel.

so in my answer must i just give the parallel vector, not the anti parallel one?
 

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