[tex]\bf \textit{distance between 2 points}\\ \quad \\
\begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
&({{ 5}}\quad ,&{{ 1}})\quad
% (c,d)
&({{ 5}}\quad ,&{{ -6}})
\end{array}\qquad
% distance value
d = \sqrt{({{ x_2}}-{{ x_1}})^2 + ({{ y_2}}-{{ y_1}})^2}
\\\\\\
d=\sqrt{(5-5)^2+(-6-1)^2}\implies d=\sqrt{0^2+(-5)^2}\implies d=\sqrt{25}[/tex]
