Answer: 2.
- A 0
- B 1
- C 3
- D 2
Correct answer: D. 2
Explanation: b x c = (j+k) x (k+i) = j x k + j x i + k x k + k x i = i + (-j) + 0 + j = i. Wait: j x k = i, j x i = -k, k x k = 0, k x i = j. So b x c = i - k + j = i+j-k. a.(b x c) = (i+j).(i+j-k) = 1+1+0 = 2.
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