Answer: [tex]19.31\ ft[/tex]
Step-by-step explanation:
Given
The tower is at a height of [tex]h=20\ ft[/tex]
the angle of depression is [tex]15^{\circ}[/tex]
Suppose the surfer is x ft away from the base of the tower
[tex]\therefore \text{From the figure, we can write}\\\\\Rightarrow \cos 15^{\circ}=\dfrac{x}{h}\\\\\Rightarrow x=h\cos 15^{\circ}\\\Rightarrow x=20\cos 15^{\circ}\\\Rightarrow x=19.31\ ft[/tex]
Therefore, the surfer is at a distance of 19.31 ft from the base of the tower.