Given:
The boy is the observer while the flying bird is the object of observation.
To name:
The angle formed by the horizontal line and the boy’s line of sight.
Step-by-step explanation:
We know that,
An angle of elevation is defined as an angle between the horizontal plane and line of sight from the observer's eye to some object above.
Here,
The boy is the observer while the flying bird above is the object of observation.
Therefore, the angle formed by the horizontal line and the boy’s line of sight is the angle of elevation.
Final answer:
Angle of elevation