85√2.
1) Since we have a right triangle with two congruent angles, then we can find the hypotenuse by using a trigonometric ratio:
![\begin{gathered} \sin (45)=(85)/(y) \\ \frac{\sqrt[]{2}}{2}=(85)/(y) \\ y\sqrt[]{2}=170 \\ y=\frac{170}{\sqrt[]{2}}*\frac{\sqrt[]{2}}{\sqrt[]{2}} \\ y=\frac{170\sqrt[]{2}}{2} \\ y=85\sqrt[]{2} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/1yyg6wr1780u80by1o0erxwc03qsbik61s.png)
2) So the hypotenuse is 85√2
Another way to find that out is considering that the hypotenuse would be the diagonal of a square (since we have two 45º angles and one right angle (90º) and the diagonal of a square is a√2 then 85√2