Vectors - Scalar (Dot) Product

Vectors - Scalar (Dot) Product

  1. Evaluate \(\left( 2\mathbf{i}+3\mathbf{j}-\mathbf{k} \right)\cdot \left( \mathbf{i}-5\mathbf{k} \right)\).
  2. Evaluate \(\left( \mathbf{i}-5\mathbf{j}+4\mathbf{k} \right)\cdot \left( 3\mathbf{i}-2\mathbf{j}-3\mathbf{k} \right)\).
  3. Evaluate \(\left( -6\mathbf{i}+\mathbf{j} \right)\cdot \left( \mathbf{i}-\mathbf{j}-8\mathbf{k} \right)\).
  4. Find the acute angle between direction vectors \(\left( 2\mathbf{i}+3\mathbf{j}-\mathbf{k} \right)\) and \(\left( \mathbf{i}-5\mathbf{k} \right)\).
  5. Find the acute angle between direction vectors \(\left( \mathbf{i}-5\mathbf{j}+4\mathbf{k} \right)\) and \(\left( 3\mathbf{i}-2\mathbf{j}-3\mathbf{k} \right)\).
  6. Find the acute angle between direction vectors \(\left( -6\mathbf{i}+\mathbf{j} \right)\) and \(\left( \mathbf{i}-\mathbf{j}-8\mathbf{k} \right)\).

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Answer:(a) \(7\) (b) \(1\) (c) \(-7\) (d) \(68.5^\circ\) (e) \(88.1^\circ\) (f) \(81.9^\circ\)

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