Question Detail
Question
Find the angle between these two vectors: A = 2i + 6j + 3k and B = 5i - 3j - 2k.
Correct Answer
Option D is the correct answer.
Detailed Explanation
A·B = (2)(5) + (6)(-3) + (3)(-2) = 10 - 18 - 6 = -14. |A| = √(4 + 36 + 9) = √49 = 7. |B| = √(25 + 9 + 4) = √38 ≈ 6.164. cos θ = -14/(7 × 6.164) = -14/43.15 = -0.3245. θ = cos⁻¹(-0.3245) = 109°.
Hint
Use dot product: A·B = |A||B|cos θ.