Answer
$\theta = 60^{\circ}$
Work Step by Step
When $\frac{y}{L} = 0$, the force $F_a$ is applied at the location of the hinge. Since $T = 0$ when $\frac{y}{L} = 0$, then the force $F_h$ is equal and opposite to the force $F_a$. Note that $F_h = 300~N$ when $\frac{y}{L} = 0$
We can consider the point $\frac{y}{L} = 1$ to find the angle $\theta$:
$T~cos~\theta = 300~N$
$(600~N)~cos~\theta = 300~N$
$cos~\theta = 0.5$
$\theta = cos^{-1}~(0.5)$
$\theta = 60^{\circ}$
