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Homework Help: The angle between P and Q?

  1. Jul 13, 2018 #1
    • Member has been warned for showing no own effort.
    1. The problem statement, all variables and given/known data
    The resultant R of vectors P and Q is perpendicular to P and R=P both, then the angle between P and Q is what?
    Now, what is the concept behind it? Could you provide me with an image of the resultant perpendicular to two vectors so that I can understand the concept and start solving the problem?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jul 13, 2018 #2


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    Staff Emeritus
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    What do you mean by "is perpendicular to P and R=P both"? I don't know how to parse that.
  4. Jul 13, 2018 #3
    nither I understand what it means. The question says like this.
  5. Jul 13, 2018 #4


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    Science Advisor

    Perhaps it means "R is perpendicular to P and |R| = |P|". Or perhaps "R is perpendicular to P and R = P". Or whatever notation. That is, the vector R is at right angles to the vector P, and the length of R equals the length of P.
  6. Jul 13, 2018 #5


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    Homework Helper
    Gold Member

    I agree with stevendaryl, the question is not easy to understand formulated like this, but here is my guess:

    The resultant vector ##\vec{R}## is the sum of the two vectors ##\vec P ## and ##\vec Q ##. You know the direction and the length of ##\vec P ##, where the latter is identical with the length of ##\vec R ##. Therefore you know the lengths of two vectors and their angle with respect to each other. By drawing this constellation, there is only one possibility for ##\vec Q ## to fit between them. Try to draw it, show your attempt and it's easier to help you.
  7. Jul 13, 2018 #6


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    Staff: Mentor

    Please report to the mentors those cases, in which the OP doesn't show any effort to tackle his problem, instead of answering it. If you think it is a general problem of understanding rather than a homework problem, then please also report it, such that we can move it to a technical forum.

    @Indranil : If you're in doubt what to do, you can always ask in advance for guidance by a mentor, or report your own post to be evaluated.

    Thanks for your understanding.
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