Answer
$d = 48.3~ft$
Work Step by Step
We can find $\theta$:
$\theta = \frac{57.3~S}{R}$
$\theta = \frac{(57.3)(485~ft)}{600~ft}$
$\theta = 46.3^{\circ}$
We can find the value of $d$:
$d = R~(1-cos~\frac{\theta}{2})$
$d = (600~ft)(1-cos~\frac{46.3^{\circ}}{2})$
$d = 48.3~ft$