how do i use coordinate geometry to find the midpoint AB?

To find the mid point of the line segment Ab you have to get the coordinate sof point A and B respectively.
Mid point formular can be represented as follows
[tex]\begin{gathered} \text{mid point = (}\frac{x_1+x_2}{2},\frac{y_1+y_2}{2}\text{)\_} \\ \end{gathered}[/tex]A(-2,-2 ) and B(3,7)
[tex]\begin{gathered} \text{mid point}=(\frac{-2+3}{2},\frac{-2+7}{2}) \\ \text{mid point=(}\frac{1}{2},\frac{9}{2}\text{)} \end{gathered}[/tex]