[tex]\bf \textit{distance between 2 points}\\ \quad \\
\begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
C&({{ -1}}\quad ,&{{ 4}})\quad
% (c,d)
D&({{ 2}}\quad ,&{{ 0}})
\end{array}\qquad
% distance value
d = \sqrt{({{ x_2}}-{{ x_1}})^2 + ({{ y_2}}-{{ y_1}})^2}
\\\\\\
CD=\sqrt{[2-(-1)]^2+(0-4)^2}\implies CD=\sqrt{(2+1)^2+(-4)^2}
\\\\\\
CD=\sqrt{9+16}\implies CD=\sqrt{25}\implies CD=5[/tex]
