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How does the determinant of a matrix with vector columns relate to the scalar triple product?

For three-dimensional vectors u,v,wu, v, w, the scalar triple product u⋅(v×w)u\cdot(v\times w) is equal to the determinant of the matrix formed by placing these vectors as columns, denoted as det⁡[u v w]\det[u\ v\ w].

Conditions

  • The vectors u,v,wu, v, w are three-dimensional.
  • The vectors are arranged as columns in the matrix.

Reasoning, step by step

  1. Identify the three 3D vectors u,v,wu, v, w.
  2. Construct a 3x3 matrix with u,v,wu, v, w as its columns.
  3. Calculate the determinant of this matrix.
  4. Compute the cross product v×wv \times w.
  5. Compute the dot product u⋅(v×w)u \cdot (v \times w).
  6. Verify that the determinant equals the scalar triple product.

Example

The script states: "For three-dimensional vectors, u⋅(v×w)=det⁡[u v w]u\cdot(v\times w)=\det[u\ v\ w], with the vectors as columns."

Common misconceptions

  • Placing the vectors as rows instead of columns (which yields the same determinant value but differs in geometric orientation interpretation in some contexts, though strictly det⁡(A)=det⁡(AT)\det(A) = \det(A^T)).
  • Confusing the scalar triple product with the vector triple product.
  • Thinking the determinant is a vector rather than a scalar.

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