What is the angle between the two lines with direction vectors and ?

Answer and explanation

Correct answer: A.

  1. Step 1: Compute dot product: .
  2. Step 2: Compute magnitudes: , and .
  3. Step 3: Cosine of angle: .
  4. Step 4: Angle is .
Answer
\arccos(\frac{4}{9}).
Why not the others: '' assumes parallel lines; '' assumes ; '' assumes perpendicular lines with dot product zero.

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