Prove that a rotation matrix preserves distance

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SUMMARY

A rotation matrix in R3, defined as an orthogonal 3x3 matrix, preserves distance, meaning that for any vector v, the length of the transformed vector |A.v| equals the length of the original vector |v|. This property is inherent to the definition of rotation matrices, as they represent rigid transformations that do not alter the length of vectors. The discussion highlights the need for a clear definition of a rotation matrix and suggests that the proof can be approached similarly to the R2 case, potentially using geometric interpretations or algebraic properties of orthogonal matrices.

PREREQUISITES
  • Understanding of orthogonal matrices in linear algebra
  • Familiarity with vector norms and their properties
  • Knowledge of rotation matrices in R2 and R3
  • Basic concepts of rigid transformations in Euclidean space
NEXT STEPS
  • Study the properties of orthogonal matrices in linear algebra
  • Learn about the geometric interpretation of rotation matrices in R3
  • Explore proofs of distance preservation in R2 and their extension to R3
  • Investigate applications of rotation matrices in computer graphics and robotics
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Students and educators in mathematics, particularly those studying linear algebra and transformations, as well as professionals in fields involving computer graphics and physics simulations.

gottfried
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Homework Statement


Prove that a rotation matrix in R3 preserves distance.

Such that if A is a 3*3 orthogonal rotation matrix then |A.v|=|v|.

I know one can prove this is in R2 by using a trig representation of a rotation matrix and then simplifying. Is there an analogue method in R3 or some other more elegant way. A hint/push in the right direction would be nice.
 
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I am puzzled by the question. What, exactly, are you using as a definition of "rotation matrix". If it is the obvious- that it corresponds to a rotation- the fact that it does not change length follows immediately from the definition of "rotation".
 

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