Tethered Airplane Find The Angle Of Elevation?

Find the Angle of Elevation? - tethered airplane

Model Airplane Jake is by a rope, which is 120 meters long bound. the aircraft flew 82 meters above the ground. Here you will find the elevation angle of the aircraft.

So, if I angle angle = u if u) = let (82/120 and if I arctan on both sides i get u = arctan (82/120) I thought it was the right answer, but the book says their No. Can anyone help me please and tell me how you do it right? Thanks