Answer
$\theta = 71^{\circ}$
Work Step by Step
In part (b), we found the following components of the force on the ladder from the ground:
$F_x = 280~N$
$F_y = 833~N$
We can find the angle $\theta$ above the horizontal of this force:
$tan~\theta = \frac{F_y}{F_x}$
$\theta = tan^{-1}~\frac{F_y}{F_x}$
$\theta = tan^{-1}~\frac{833~N}{280~N}$
$\theta = 71^{\circ}$
