[tex]~~~~~~~~~~~~\textit{distance between 2 points} \\\\ P(\stackrel{x_1}{5}~,~\stackrel{y_1}{7})\qquad Q(\stackrel{x_2}{-1}~,~\stackrel{y_2}{-1})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ PQ=\sqrt{[-1 - 5]^2 + [-1 - 7]^2}\implies PQ=\sqrt{(-6)^2 + (-8)^2} \\\\\\ PQ=\sqrt{36+64}\implies PQ=10[/tex]