What is the Vector Identity for \vec A and \hat n?

In summary, we want to show that an arbitrary vector \vec A can be expressed as the sum of its projections on a fixed unit vector \hat n and its orthogonal complement, W^\bot. This can be proven using the Vector Triple Product Identity and the given expressions for the projections.
  • #1
Reshma
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6
Let [itex]\vec A[/itex] be an arbitrary vector and let [itex]\hat n[/itex] be a unit vector in some fixed direction. Show that
[tex]\vec A = (\vec A .\hat n)\hat n + (\hat n \times \vec A)\times \hat n.[/tex]
 
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  • #2
You can use the Vector Triple Product Identity on the last term:

[tex]\left( {\vec A \times \vec B} \right) \times \vec C = - \vec A\left( {\vec B \cdot \vec C} \right) + \vec B\left( {\vec A \cdot \vec C} \right)[/tex]
 
  • #3
The vector [tex]\vec A[/tex] is expressed as the sum of its projections on [tex]W= \mathcal{L} (\hat{n})[/tex] and [tex]W^\bot[/tex].

Prove that the two terms represent these.
 
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1. What is a vector identity?

A vector identity is an equation that relates different vector quantities. It is used to prove mathematical relationships between vectors, such as the dot product or cross product.

2. How do you prove a vector identity?

To prove a vector identity, you must manipulate the given equations using mathematical properties and rules, until both sides of the equation are equal. This involves simplifying and rearranging terms, and sometimes using geometric interpretations of vector operations.

3. What are some common vector identities?

Some common vector identities include the distributive law, the commutative law, and the associative law for vector addition and multiplication. Other identities involve the dot product, cross product, and triple product of vectors.

4. Why are vector identities important?

Vector identities are important because they allow us to simplify and solve complex vector equations. They also provide a deeper understanding of the relationships between different vector quantities, and can be applied in various fields such as physics, engineering, and mathematics.

5. Can vector identities be proven using real-life applications?

Yes, vector identities can be applied to real-life situations, such as calculating forces and velocities in physics or analyzing motion and geometry in engineering. By using vector identities, we can accurately describe and predict the behavior of physical systems.

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