[tex]~~~~~~~~~~~~\textit{distance between 2 points} \\\\ (\stackrel{x_1}{5}~,~\stackrel{y_1}{9})\qquad (\stackrel{x_2}{-7}~,~\stackrel{y_2}{-7})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ d=\sqrt{(~~-7 - 5~~)^2 + (~~-7 - 9~~)^2} \implies d=\sqrt{( -12 )^2 + ( -16 )^2} \\\\\\ d=\sqrt{ 144 + 256 } \implies d=\sqrt{ 400 }\implies d=20[/tex]
