Trong không gian, cho hai vectơ $\overset{\rightarrow}{AB}$ và $\overset{\rightarrow}{BC}$. Vectơ $\overset{\rightarrow}{AC}$ bằng
$\overset{\rightarrow}{AB}$.
$\overset{\rightarrow}{AB} - \overset{\rightarrow}{BC}$.
$- \overset{\rightarrow}{AC} - \overset{\rightarrow}{BC}$.
$\overset{\rightarrow}{AB} + \overset{\rightarrow}{BC}$.