Answer: a.(b x c) = 0.
- A a x b x c = 0
- B a.(b x c) = 1
- C a.(b x c) = 0
- D a + b + c = 0
Correct answer: C. a.(b x c) = 0
Explanation: Vectors a, b, c are coplanar if and only if their scalar triple product a.(b x c) = 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