distance between (x1,y1) and (x2,y2) is
[tex]D= \sqrt{(x_2-x_1)^2+(y_2-y_1)^2} [/tex]
so the distance between (7,8) and (1,-17) is
[tex]D= \sqrt{(1-7)^2+(-17-8)^2} [/tex]
[tex]D= \sqrt{(-6)^2+(-25)^2} [/tex]
[tex]D= \sqrt{36+225} [/tex]
D=√261
D=3√29
the exact distance is 3√29 units