Answer: 0.
- A 0
- B 6
- C 12
- D −12
Correct answer: A. 0
Explanation: |a + b|² = |a|² + |b|² + 2a·b gives 25 = 9 + 16 + 2a·b, so a·b = 0.
Triangle law of vector addition: placing vector b at the head of vector a, the diagonal from the start to the final head gives the resultant a + b.
Concept context
Vectors, dot product, cross product, and geometric applications