Answer
The stone will travel 35 feet.
Work Step by Step
In part (a), when $h=0$:
$D = \frac{v^2~sin~(2~\theta)}{32}$
We can find $D$ when $\theta = 30^{\circ}$ and $v = 36~ft/s$:
$D = \frac{(36~ft/s)^2~sin~[(2)(30^{\circ})]}{32}$
$D = \frac{(36~ft/s)^2~sin~(60^{\circ})}{32}$
$D = 35~ft$
The stone will travel 35 feet.
