Points and vectors

Let $ABC$ be a triangle with $A=[1;2;-3]$, $B=[-3;3;-2]$ and $C=[-1;1;-1]$. Find its perimeter.

In the parallelogram $ABCD$ shown in the picture, $G$ is the midpoint of $CD$, $F$ is the midpoint of $BC$ and $\overrightarrow{u}=\overrightarrow{CG}$, $\overrightarrow{v}=\overrightarrow{CF}$, $\overrightarrow{a}=\overrightarrow{AD}$ and $\overrightarrow{b}=\overrightarrow{AC}$. Express vectors $\overrightarrow{a}$ and $\overrightarrow{b}$ as a linear combination of vectors $\overrightarrow{u}$ and $\overrightarrow{v}$.

$S$ is the midpoint of $AB$. $A=[5;-7]$, $S=[0;-9]$. Find the coordinates of $B$.

Let $ABC$ be a triangle. In the picture, the midpoint of the side $BC$ and the centroid of the triangle are indicated. Out of the following vector relations select the one that is not true.