\(The\ distance\ between\ A(x_A;\ y_A)\ and\ B(x_B;\ y_B):\\\\d=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}\\\\------------------------------\\\\R(-1;\ 0);\ S(8;\ 6)\\\\subtitute\\\\d=\sqrt{(8-(-1))^2+(6-0)^2}=\sqrt{9^2+6^2}=\sqrt{81+36}\\\\=\boxed{\sqrt{117}}=\sqrt{9\cdot13}=\sqrt9\cdot\sqrt{13}=3\sqrt{13}\)
