The coordinates of the point is,
[tex]\begin{gathered} (x,y)=(5,8) \\ (x_1,y_1)=(5,10) \end{gathered}[/tex]The slope of the slope of the line containing the points (5, 8) and (5, 10) is,
[tex]\begin{gathered} m=\frac{y_1-y}{x_1-x} \\ m=\frac{10-8}{5-5}=\frac{2}{0} \end{gathered}[/tex]Since the denominator of the fraction is zero, the slope is undefined.
The x coordinates of the points are same. Hence, the line passing through the points (5, 8) and (5, 10) are parallel to the Y axis. So, the line is vertical.
Therefore, the slope is undefined and the line is vertical.