How can I prove that the dot product is distributive?

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SUMMARY

The discussion focuses on proving the distributive property of the dot product for vectors A, B, and C, specifically that A.(B+C) = A.B + A.C. The participants emphasize the need to generalize this proof beyond Cartesian coordinates, utilizing the metric tensor instead of the Kronecker delta. The initial approach involves using the definition of the dot product, which states that the dot product equals the product of the lengths of the vectors multiplied by the cosine of the angle between them. A suggestion is made to first prove the property in Cartesian coordinates before extending the proof to arbitrary coordinate systems.

PREREQUISITES
  • Understanding of vector operations, specifically the dot product.
  • Familiarity with the concept of metric tensors in non-Cartesian coordinate systems.
  • Knowledge of trigonometric relationships, particularly cosine in relation to angles between vectors.
  • Basic linear algebra concepts, including vector addition and scalar multiplication.
NEXT STEPS
  • Study the properties of metric tensors and their applications in different coordinate systems.
  • Learn how to perform vector transformations between Cartesian and non-Cartesian coordinates.
  • Explore proofs of vector operations in Cartesian coordinates to establish foundational understanding.
  • Investigate the implications of the dot product in various mathematical contexts, such as physics and engineering.
USEFUL FOR

Students in advanced mathematics or physics courses, educators teaching vector calculus, and anyone interested in the theoretical foundations of vector operations and their applications in various coordinate systems.

Mathematicsresear
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Homework Statement



Prove that for vectors A,B and C, A.(B+C)=A.B+A.C and prove the property that for two vectors, A and B the dot product is equal to A^ie_i . B^je_j = e_i.e_jA^iB^j

Homework Equations


Only use the definition where for two vectors a and b the (length of a)(length of b)cost =a.b
Generalize for an arbitrary coordinate system (not necessarily cartesian). Moreover, I'm not allowed to assume that the basis are the standard, I,j,k basis vectors. So the metric tensor is not the kronecker delta. I mean that I shouldn't assume that I'm just working in cartesian coordinates.

The Attempt at a Solution


For the first, I got length of A length ofB+C cost but I'm not sure what to do after that.
 
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Mathematicsresear said:

Homework Statement



Prove that for vectors A,B and C, A.(B+C)=A.B+A.C and prove the property that for two vectors, A and B the dot product is equal to A^ie_i . B^je_j = e_i.e_jA^iB^j

Homework Equations


Only use the definition where for two vectors a and b the (length of a)(length of b)cost =a.b
Generalize for an arbitrary coordinate system (not necessarily cartesian). Moreover, I'm not allowed to assume that the basis are the standard, I,j,k basis vectors. So the metric tensor is not the kronecker delta. I mean that I shouldn't assume that I'm just working in cartesian coordinates.

The Attempt at a Solution


For the first, I got length of A length ofB+C cost but I'm not sure what to do after that.

Why not prove it first for cartesian coordinates, then develop the expression in other coordinate systems by transformations?
 

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