In the given problem, the chord of the circle forms right triangles with a perpendicular line that passes through the center of the circle. Therefore, the length of the chord is bisected and we get the following triangles:
We can use the Pythagorean theorem to determine the value of the radius:

Solving the operations:

Now we take the square root to both sides:
![\begin{gathered} r=\sqrt[]{85625} \\ r=292.6 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/g4n1njfirvrhjsii6wl042xj1tle8utiig.png)
Therefore, the radius of the arc is 292.6 ft.