Plane geometry

Given points $A=[2;m]$ and $B=[-1;0]$, find $m\in \mathbb{R}$ such that the line $p$ is parallel to the line passes through the points $A$, $B$. $$\begin{array}{rlr}p:x& =3+2t,& \\ y& =5-t;t\in \mathbb{R}\end{array}$$

Given lines $p$ and $q$, find $m\in \mathbb{R}$ such that the lines $p$ and $q$ are parallel. $$p:2x+my-3=0,\begin{array}{rlr}q:x& =1+t,& \\ y& =2-t;t\in \mathbb{R}\end{array}$$

Given points $A=[0;5]$, $B=[6;1]$, $C=[7;9]$, find the direction vector of the line passing through the point $A$ and the midpoint of the segment $BC$ (i.e. the median of the triangle $ABC$ through the vertex $A$).

Consider the points $A=[0;5]$, $B=[6;1]$, $C=[7;9]$ and the triangle $ABC$. Find the direction vector of the line which is the perpendicular bisector of the side $b$ (i.e. the line through the midpoint of the side $AC$ which is perpendicular to the segment $AC$).