Answer:
The correct option is;
17,202 feet
Step-by-step explanation:
The distance from the observer to the bird is given as 21,000 ft
The angle between the line of flight of the bird to the horizontal line from its nest = 35°
With the triangle BNO = A right triangle, we have;
The distance of the bird from its nest = Adjacent leg of the right triangle
The distance of the observer from the bird = Hypotenuse length
Which by trigonometric relations gives;
21,000×cos(35 degrees) = The distance of the bird from its nest = 17,202.2 feet ≈ 17,202 feet.