Why Use Double Modulus Signs in Vector Dot Products?

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SUMMARY

The discussion clarifies the use of double modulus signs in vector dot products, specifically comparing the expressions u.v=|u||v|cosθ and u.v=||u||||v||cosθ. Both expressions represent the same mathematical concept, where the cosine of the angle between two vectors is multiplied by their magnitudes. The double modulus sign, ||u||, typically denotes the norm or length of a vector, which is essential in various mathematical contexts. Understanding this distinction is crucial for accurately interpreting vector operations in geometry.

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I'm confused regarding why the double modulus sign is used. Let's take the dot product:

u.v=|u||v|cosθ The R>H>S means that the cosine of the angle is multiplied witht the magnitudes of both vectors.
Now,
u.v=||u||||v||cosθ
Does this mean the same thing? Help?
 
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hivesaeed4 said:
I'm confused regarding why the double modulus sign is used. Let's take the dot product:

u.v=|u||v|cosθ The R>H>S means that the cosine of the angle is multiplied witht the magnitudes of both vectors.
Now,
u.v=||u||||v||cosθ
Does this mean the same thing? Help?

Typically when you see ||a|| it refers to a norm or length of a vector just for future reference. In this case it means the same thing, but in other contexts it may not.

Whenever you look at geometry and you see ||a||, then this will refer to norms and if people need to refer to distance and the space is a norm then this will be used.
 
Thanks
 

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