hmmm taking a peek at the triangles inside the park, hmmm let's notice both triangles have all interior angles of 60°, meaning the triangles are equilateral both, so all sides are equal, since we know one side is 50 yards, well, all sides are 50 yards, so the top and bottom straight-lines are both 50 each.
looking at the left and right sides, hmmm those are just sectors of a circle, both have a radius of 50 yards and a central angle of 120°.
![\textit{arc's length}\\\\ s=\cfrac{\theta \pi r}{180}~~ \begin{cases} r=radius\\ \theta =\stackrel{degrees}{angle}\\[-0.5em] \hrulefill\\ r=50\\ \theta =120 \end{cases}\qquad \implies s=\cfrac{(120)\pi (50)}{180}\implies s=\cfrac{100\pi }{3} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \stackrel{straight~lines}{2(50)}~~ + ~~\stackrel{circular~lines}{2\left( \cfrac{100\pi }{3} \right)}\implies 100+2\left( \cfrac{100(3.14) }{3} \right)~~\approx~~309~yards](https://img.qammunity.org/2023/formulas/mathematics/high-school/7olrchj0of6526nzk892r8c8qubzlfpz0m.png)