Can Geometry Help Solve This Vector Problem?

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Homework Help Overview

The discussion revolves around a vector problem involving points M, A, and B in a plane, where the relationship between the distances from M to A and B is expressed through the equation MA² - MB² = -4. Participants are tasked with showing that the product of vectors IM and AB equals -2, with I being the midpoint of segment AB.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the implications of the equation MA² - MB² = -4 and question the definitions of points A and B, as well as the meaning of the notation used. There is a discussion about whether the asterisk (*) represents the dot product. Some participants attempt to manipulate the equation but express uncertainty about the next steps.

Discussion Status

The discussion is ongoing, with participants clarifying the problem statement and addressing typographical errors. Some have provided insights into vector relationships, while others are still seeking clarity on the problem's requirements and notation.

Contextual Notes

There is confusion regarding the initial conditions of the problem, particularly the equation involving MA² and MB², which was initially misstated. Participants are also navigating the implications of vector notation and the geometric interpretation of the problem.

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Homework Statement



(E) is a group of points M from a level/plane

[tex]MA^{2}-MB^{2}=-4[/tex] And I is the center of [AB]

Homework Equations



show that IM*AB=-2 ( IM and AB have arrows on top)

The Attempt at a Solution



Well i split [tex]MA^{2}-MB^{2}=(MA-MB)(MA+MB)[/tex]

then i got : [tex]MA^{2}-MB^{2}=BA*(MA+MB)[/tex]

and i don't know where to go on from there any help?
 
Last edited:
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mtayab1994 said:

Homework Statement



(E) is a group of points M from a level/plane

[tex]MA^{2}+MB^{2}=-4[/tex] And I is the center of [AB]
This doesn't make any sense to me.

What is A? What is B? Is AB the line segment from point A to point B?
mtayab1994 said:

Homework Equations



show that IM*AB=-2 ( IM and AB have arrows on top)

The Attempt at a Solution



Well i split [tex]MA^{2}-MB^{2}=(MA-MB)(MA+MB)[/tex]

then i got : [tex]MA^{2}-MB^{2}=BA*(MA+MB)[/tex]

and i don't know where to go on from there any help?
 
Mark44 said:
This doesn't make any sense to me.

What is A? What is B? Is AB the line segment from point A to point B?

My fault AB is a line segment and I is the center of it.
 
mtayab1994 said:

Homework Statement



(E) is a group of points M from a level/plane

[tex]MA^{2}+MB^{2}=-4[/tex] And I is the center of [AB]
...
I think this is impossible! → [itex]MA^{2}+MB^{2}=-4[/itex]

Do you mean? → [itex]MA^{2}-MB^{2}=-4[/itex]
 
SammyS said:
I think this is impossible! → [itex]MA^{2}+MB^{2}=-4[/itex]

Do you mean? → [itex]MA^{2}-MB^{2}=-4[/itex]


Yea sorry my fault that was a typo its MA^2-MB^2=-4
 
Any ideas?
 
What does this mean?
mtayab1994 said:
show that IM*AB=-2 ( IM and AB have arrows on top)
Does * represent the dot product?
 
Mark44 said:
What does this mean?

Does * represent the dot product?

Yes.
 
mtayab1994 said:

Homework Statement



(E) is a group of points M from a level/plane

[tex]MA^{2}-MB^{2}=-4[/tex] And I is the center of [AB]

Homework Equations



show that IM*AB=-2 ( IM and AB have arrows on top)

The Attempt at a Solution



Well i split [tex]MA^{2}-MB^{2}=(MA-MB)(MA+MB)[/tex]

then i got : [tex]MA^{2}-MB^{2}=BA*(MA+MB)[/tex]

and i don't know where to go on from there any help?

mtayab1994 said:
My fault AB is a line segment and I is the center of it.
Since "IM and AB have arrows on top", and "AB is a line segment", I take it that these are all vectors and, for example, [itex]\vec{MB}[/itex] is a vector from point M to point B.

If that's the case, then notice that [itex]\vec{MA}=\vec{MI}+\vec{IA}\,.[/itex] Do similar for [itex]\vec{MB}[/itex]

Notice that[itex]\vec{IB}=-\vec{IA}\,.[/itex]

Now look at [itex]\vec{MA}+\vec{MB}[/itex] again.
 

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