Standing due south of a tower 50m high, the angle of elevation of the top is 26^{o}^{.} What is the angle of elevation after walking a distance of 120m due east?
starting distance South of the tower's base is $d_1= \dfrac{50}{\tan(26^\circ)}$ meters
Moving 120m East, the new distance from the tower's base is $d_2=\sqrt{d_1^2 + 120^2}$ meters.
new angle of elevation = $\arctan\left(\dfrac{50}{d_2}\right)$