The magnitude of the resultant of two vectors lies between the range of their sum and the difference. For vectors of magnitudes 4 units and 8 units, the possible resultant must be between:
\(\ \ |8 - 4| = 4 \text{units} \quad \text{and} \quad 8 + 4 = 12 \text{units}.\)
Show that the line passing through the points A $(0, -1, -1)$ and B $(4, 5, 1)$ intersects the line joining points C $(3, 9, 4)$ and D $(-4, 4, 4)$.