[tex]\bf ~~~~~~~~~~~~\textit{distance between 2 points} \\\\ (\stackrel{x_1}{3}~,~\stackrel{y_1}{6})\qquad (\stackrel{x_2}{1}~,~\stackrel{y_2}{9})\qquad \qquad d = \sqrt{( x_2- x_1)^2 + ( y_2- y_1)^2} \\\\\\ d=\sqrt{(1-3)^2+(9-6)^2}\implies d=\sqrt{(-2)^2+3^2} \\\\\\ d=\sqrt{13}\implies d\approx 3.6056\implies \stackrel{\textit{rounded up}}{d=3.6}[/tex]
