Condition for Equal Magnitudes of Projection Vectors?

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Homework Help Overview

The discussion revolves around the conditions under which the sum of the squares of the magnitudes of the projection vectors of two vectors \( \vec{a} \) and \( \vec{b} \) equals one, specifically when the angle between them is not 90 degrees. Participants are exploring the relationship between these projections and the cosine of the angle between the vectors.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Some participants attempt to establish a relationship between the projections and the magnitudes of the vectors, noting that equal magnitudes of the projections occur when the magnitudes of the vectors are equal. Others express uncertainty about the question's intent and suggest deriving an expression for the cosine of the angle in terms of the magnitudes of the vectors.

Discussion Status

The discussion is ongoing, with participants sharing their interpretations and attempting to clarify the problem. There is recognition of the complexity of the question, and some guidance has been offered regarding the relationship between the projections and the vectors' magnitudes.

Contextual Notes

Participants are working under the constraint that the angle between the vectors is not 90 degrees, which may influence their reasoning and assumptions about the projections.

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Homework Statement


The angle between two vectors a and b is ∅, where ∅≠90°. Under what conditions will |Projab|2 + |Projba|2 = 1?


Homework Equations


|Pab|= |\vec{a}\bullet\vec{b}|/|\vec{b}|

|Pba|= |\vec{a}\bullet\vec{b}|/|\vec{a}|


The Attempt at a Solution


I know that |Pab|=|Pba| when |\vec{a}|=|\vec{b}|

I'm not sure where I go from there.

Any help is appreciated, thanks.
 
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anonymoususer said:

Homework Statement


The angle between two vectors a and b is ∅, where ∅≠90°. Under what conditions will |Projab|2 + |Projba|2 = 1?


Homework Equations


|Pab|= |\vec{a}\bullet\vec{b}|/|\vec{b}|

|Pba|= |\vec{a}\bullet\vec{b}|/|\vec{a}|


The Attempt at a Solution


I know that |Pab|=|Pba| when |\vec{a}|=|\vec{b}|

I'm not sure where I go from there.

Any help is appreciated, thanks.

Looks to me like they just want you to derive an express for cos(∅) in terms of |a| and |b|.
 
Dick said:
Looks to me like they just want you to derive an express for cos(∅) in terms of |a| and |b|.

I think it's a little more complex than that. I am a little confused on what the question is asking though.
 
anonymoususer said:
I think it's a little more complex than that. I am a little confused on what the question is asking though.

I worked through it and that's the only thing I can figure they could be asking.
 

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