If A = ai + bj and B = ci + dj, what is the expression for A · B?

Practice Questions

Q1
If A = ai + bj and B = ci + dj, what is the expression for A · B?
  1. ac + bd
  2. ab + cd
  3. ad + bc
  4. a + b + c + d

Questions & Step-by-Step Solutions

If A = ai + bj and B = ci + dj, what is the expression for A · B?
  • Step 1: Identify the vectors A and B. A = ai + bj and B = ci + dj.
  • Step 2: Understand that the dot product (A · B) involves multiplying the corresponding components of the vectors.
  • Step 3: Multiply the 'i' components: a (from A) and c (from B) to get ac.
  • Step 4: Multiply the 'j' components: b (from A) and d (from B) to get bd.
  • Step 5: Add the results from Step 3 and Step 4 together: ac + bd.
  • Step 6: Write the final expression for the dot product: A · B = ac + bd.
  • Dot Product – The dot product of two vectors is calculated by multiplying their corresponding components and summing the results.
  • Vector Notation – Understanding the representation of vectors in terms of their components along the i and j axes.
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