In a square, all the sides are the same length.
![PQ=QR=SR=SP](https://img.qammunity.org/2023/formulas/mathematics/college/z9t45oaqnujnps1rn9lwcczkc2r6sydrfq.png)
So, to find the length of the segment SR you can find the length of the segment QR using the formula of the distance between two points, that is:
![\begin{gathered} d=\sqrt[]{(x_2-x_1)^2+(y_2-y_1)^2^{}} \\ \text{ Where d is the distance between two points } \\ A(x_1,y_1)\text{ and} \\ B(x_2,y_2) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8poid5el1ml6yzpluqtpbnvg0g5v725r85.png)
So, in this case, you have
![\begin{gathered} Q(7,0) \\ R(5,-8) \\ d=\sqrt[]{(5_{}-7)^2+(-8-0)^2} \\ d=\sqrt[]{(-2)^2+(-8)^2} \\ d=\sqrt[]{4+64} \\ d=\sqrt[]{68} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/3px394nolwlhrapcphfefn4eq8n89bssv9.png)
Therefore, the length of the segment SR is
![\sqrt[]{68}](https://img.qammunity.org/2023/formulas/mathematics/college/wr916z4re21gy0bdy2v2uhcq2gmpc5k4ec.png)