Mathematics

The key insight is that a position vector tells you where a point sits in space, and a displacement vector tells you how to move from one point to another. Since $\overrightarrow{AB}$ represents the displacement from $A$ to $B$, you can find $B$ by adding this displacement to $A$'s position. Think of it as: starting position plus the journey equals ending position.

The key insight is that a position vector tells you where a point sits in space, and a displacement vector tells you how to move from one point to another. Since $\overrightarrow{AB}$ represents the displacement from $A$ to $B$, you can find $B$ by adding this displacement to $A$'s position. Think of it as: starting position plus the journey equals ending position.