The diagram indicating the light tower is below.
Answer: Tower has to be 86.45 ft high.
Step-by-step explanation: The second attachment shows the right triangle formed by the tower, the floor and the point the light will shine.
Using trigonometric relations among the angle and the sides of the triangle we will have:
[tex]tan(51)=\frac{h}{70}[/tex]
h = 70*tan(51)
h = 86.45
The tower has to be 86.45 ft tall for the angle of depression to be 51°
