Two vectors A→ and B→ lie in one plane. Vector C→ lies in a different plane. Then, A→+B→+C→

The resultant of three vectors is zero only if they can form a triangle. But three vectors lying in different planes cannot form a triangle.A→+B→ lies in a plane. Since C →lies in a different plane, (A→+B→) and C→ cannot lie in the plane of (A→+B→).