Question 859130
Draw a diagram. You'll see that you are looking for the hypotenuse (air distance from observation point to the boat) and you have the adjacent side (height of the cliff).


Cosine of the angle is the quotient of the adjacent side and hypotenuse.
{{{cos30=2000/h}}}


Or, secant of the angle is the other way around, quotient of the hypotenuse and the adjacent side.
{{{sec30=h/2000}}}
{{{h = 2000*sec30}}}
h = 2309.4 m to 1 dec. point.