[tex]\bf ~~~~~~~~~~~~\textit{distance between 2 points} \\\\ (\stackrel{x_1}{8}~,~\stackrel{y_1}{10})\qquad (\stackrel{x_2}{5}~,~\stackrel{y_2}{-10})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ d = \sqrt{(5-8)^2+(-10-10)^2}\implies d=\sqrt{(-3)^2+(-20)^2} \\\\\\ d=\sqrt{409}\implies d\approx 20.22[/tex]
