# The angle between P and Q?

Member has been warned for showing no own effort.

## Homework Statement

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?

## The Attempt at a Solution

stevendaryl
Staff Emeritus
What do you mean by "is perpendicular to P and R=P both"? I don't know how to parse that.

What do you mean by "is perpendicular to P and R=P both"? I don't know how to parse that.
nither I understand what it means. The question says like this.

mjc123
Homework Helper
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.

stockzahn
Homework Helper
Gold Member

## Homework Statement

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?

## The Attempt at a Solution

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.

• stevendaryl
fresh_42
Mentor
2021 Award
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.