Product of two magnitude of vectors

In summary, the conversation discusses a question involving the cosine rule and the dot product of vectors. It is determined that the question is unsolvable as stated, but changing it to the dot product of the vectors may resolve this issue. The speaker expresses gratitude for the help provided by haruspex.
  • #1
songoku
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Homework Statement
Let A, B, C and D are 4 points in 3 dimensional space. If |AB| = 3, |BC| = 7, |CD| = 11 and |DA| = 9, calculate |AC| . |BD|
Relevant Equations
magnitude of vector

dot product
I don't really know where to start. Trying to use cosine rule but failed because no information about angle.
Thanks
 
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  • #2
Your question as stated does not involve a dot product. Did you mean ##|\vec{AC}.\vec{BD}|##?
Also, as stated, it clearly is unsolvable. You could easily vary |AC| while keeping |BD| fixed. Not sure yet if changing it to the dot product of the vectors resolves that.
 
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  • #3
haruspex said:
Your question as stated does not involve a dot product. Did you mean ##|\vec{AC}.\vec{BD}|##?
No, the question really states: ##|\vec{AC}| .| \vec{BD}|## so I interpret it as product of magnitude of vector AC and BD

Also, as stated, it clearly is unsolvable. You could easily vary |AC| while keeping |BD| fixed. Not sure yet if changing it to the dot product of the vectors resolves that.
Oh ok, I see your point.

Thank you very much haruspex
 

FAQ: Product of two magnitude of vectors

What is the definition of a product of two magnitude of vectors?

The product of two magnitude of vectors is a mathematical operation that results in a scalar quantity. It is calculated by multiplying the magnitudes of two vectors and then taking the cosine of the angle between them.

How is the product of two magnitude of vectors different from the dot product?

The product of two magnitude of vectors is different from the dot product because it only takes into account the magnitudes of the vectors, while the dot product also considers the direction of the vectors.

Can the product of two magnitude of vectors be negative?

Yes, the product of two magnitude of vectors can be negative if the angle between the two vectors is greater than 90 degrees. This indicates that the two vectors are pointing in opposite directions.

What is the significance of the product of two magnitude of vectors in physics?

The product of two magnitude of vectors is commonly used in physics to calculate the work done by a force on an object. It is also used in calculating torque, which is the rotational equivalent of force.

Are there any real-life applications of the product of two magnitude of vectors?

Yes, the product of two magnitude of vectors has various real-life applications. It is used in engineering and design to calculate the force needed to move objects, in navigation to determine the direction and speed of an object, and in computer graphics to create 3D models and animations.

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