[tex]A(x_1;\ y_1);\ B(x_2;\ y_2)\\The\ distance\ between\ A\ and\ B:\\|AB|=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\\-----------------------\\R(-1;\ 0)\to x_1=-1\ and\ y_1=0\\S(8;\ 6)\to x_2=8\ and\ y_2=6\\\\|RS|=\sqrt{(8-(-1))^2+(6-0)^2}=\sqrt{9^2+6^2}=\sqrt{81+36}=\boxed{\sqrt{107}}[/tex]
