Precalculus (6th Edition) Blitzer

$40^\circ$
Step 1. Based on the given configuration, assuming the elevation angle is $\theta$, we have $tan\theta=\frac{50}{60}=\frac{5}{6}$ Step 2. The angle $\theta$ can be found as $\theta=tan^{-1}(\frac{5}{6})\approx40^\circ$