Q: Three vectors A, B and C add up to zero. Find which is false.

(a) (A × B) × C is not zero unless B, C are parallel

(b) (A × B).C is not zero unless B, C are parallel

(c) If A , B, C define a plane, (A×B)×C is in that plane

(d) (A × B).C=|A||B||C|→ C^{2} = A^{2} + B^{2}

Ans: (b) and (d)