If A = 2i + 2j and B = 3i + 4j, what is the angle between A and B?

Practice Questions

Q1
If A = 2i + 2j and B = 3i + 4j, what is the angle between A and B?
  1. 45 degrees
  2. 60 degrees
  3. 30 degrees
  4. 90 degrees

Questions & Step-by-Step Solutions

If A = 2i + 2j and B = 3i + 4j, what is the angle between A and B?
  • Step 1: Identify the vectors A and B. A = 2i + 2j and B = 3i + 4j.
  • Step 2: Calculate the dot product of A and B. A · B = (2 * 3) + (2 * 4).
  • Step 3: Simplify the dot product. A · B = 6 + 8 = 14.
  • Step 4: Calculate the magnitude of vector A. |A| = √(2^2 + 2^2) = √(4 + 4) = √8 = 2√2.
  • Step 5: Calculate the magnitude of vector B. |B| = √(3^2 + 4^2) = √(9 + 16) = √25 = 5.
  • Step 6: Use the formula for the cosine of the angle θ: cos(θ) = (A · B) / (|A| * |B|).
  • Step 7: Substitute the values into the formula: cos(θ) = 14 / (2√2 * 5).
  • Step 8: Simplify the expression: cos(θ) = 14 / (10√2) = 0.5.
  • Step 9: Find the angle θ using the inverse cosine function: θ = cos⁻¹(0.5).
  • Step 10: Determine the angle: θ = 60 degrees.
  • Vector Operations – Understanding how to perform dot products and calculate magnitudes of vectors.
  • Trigonometry – Applying the cosine function to find angles between vectors.
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