Given , which one of the following is incorrect?
1. | a→ , b → , c → and d → must be null vectors. |
2. | The magnitude of a → + c → equals the magnitude of b → + d → . |
3. | The magnitude of a → can never be greater than the sum of the magnitudes of b → , c → and d → |
4. | b → + c → must lie in the plane of a → and d → if a → and d → are not collinear, and along the direction of a → and d → if they are collinear. |