Answer: (1/sqrt(3))(i+j+k).
- A i + j + k
- B (1/sqrt(2))(i+j+k)
- C (1/3)(i+j+k)
- D (1/sqrt(3))(i+j+k)
Correct answer: D. (1/sqrt(3))(i+j+k)
Explanation: |a| = sqrt(1+1+1) = sqrt(3). Unit vector = a/|a| = (1/sqrt(3))(i + j + k).
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