Proving the Lagrange Triple Vector Identity for Orthogonal Coordinates

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SUMMARY

The discussion centers on proving the Lagrange Triple Vector Identity, specifically the equation a × (b × c) = (a · c)b - (a · b)c, using Cartesian orthogonal coordinates. Participants clarify that a, b, and c are vectors represented by the standard basis vectors i, j, and k, which are mutually orthogonal. The confusion arises from the distinction between vector and scalar products, emphasizing that the right side of the equation results in a vector, not a scalar. The solution involves expanding both sides of the equation to demonstrate their equality.

PREREQUISITES
  • Understanding of vector operations, specifically cross product and dot product.
  • Familiarity with Cartesian orthogonal coordinates and their properties.
  • Knowledge of vector algebra and identities.
  • Ability to manipulate and simplify vector equations.
NEXT STEPS
  • Study the properties of the cross product and dot product in vector algebra.
  • Learn about vector identities and their applications in physics and engineering.
  • Explore examples of the Lagrange Triple Product Identity in various coordinate systems.
  • Practice proving vector identities using Cartesian coordinates and other orthogonal systems.
USEFUL FOR

Students of mathematics and physics, particularly those studying vector calculus and linear algebra, as well as educators teaching vector identities and their proofs.

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Homework Statement


Prove

[tex]a \times (b \times c) = (a * c)b - (a*b)c[/tex]

For orthagonal coordinates, a,b,c

Homework Equations



Cross Product and Dot Product

The Attempt at a Solution



I thought about expanding both sides out and proving they are equal, but I just realized that the left side of the theorem would give me a vector and the right side would give me a scalar. Perhaps I don't understand the theorem perfectly. Can someone explain the notion about this theorem and how I would go about proving it?
 
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I should clarify a bit

a,b,c are for cartesian orthagonal coordinates (i,j,k vectors are all normal to each other)
 
If a,b and c are vectors the right side IS a vector. (a.c)b-(a.c)c is scalar*vector minus scalar*vector. It's a vector. And you can just multiply it out.
 

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