Length of the ine segment
[tex]\begin{gathered} \text{ d =}\sqrt[]{(x2-x1)^2+(y2-y1)^2} \\ \\ d\text{ = }\sqrt[]{(8--7)^2\text{ }}+\text{ ( - 1 }-7)^2 \\ \text{ d = }\sqrt[]{\text{ 225 + 64}} \\ d\text{ = }\sqrt[]{\text{ 289}} \\ \text{ d = }\sqrt[]{289} \\ \text{ d = 17 units} \end{gathered}[/tex]