Answer
An angle of $45^{\circ}$ is the optimal angle when $h=0$
Work Step by Step
We can find the optimal angle $\theta$ when $h=0$:
$\theta = arcsin \left(\sqrt{\frac{v^2}{2v^2+64h}}\right)$
$\theta = arcsin \left(\sqrt{\frac{v^2}{2v^2+(64)(0)}}\right)$
$\theta = arcsin \left(\sqrt{\frac{v^2}{2v^2+0}}\right)$
$\theta = arcsin \left(\sqrt{\frac{1}{2}}\right)$
$\theta = arcsin \left(0.707\right)$
$\theta = 45^{\circ}$
An angle of $45^{\circ}$ is the optimal angle when $h=0$
