Question

From a boat on the lake, the angle of elevation to the top of a cliff is 18°41'. If the base of the cliff is 991 feet from the boat, how high is the cliff (to the nearest foot)?

Answer 1

Tan(18+41/60)=h/991

h=991tan(18+41/60)

h=335 ft

Answer 2

Notice the picture below, and recall your SOH CAH TOA

$\bf sin(\theta)=\cfrac{opposite}{hypotenuse} \qquad \qquad % cosine cos(\theta)=\cfrac{adjacent}{hypotenuse} \\ \quad \\\\ % tangent tan(\theta)=\cfrac{opposite}{adjacent}$

which identity has only
adjacent
opposite
and angle only ?

well   $\bf tan(\theta)=\cfrac{opposite}{adjacent}\implies tan(18^o41')=\cfrac{x}{991}$

also notice, the angles in are degrees and minutes, so, I think many or most calculators have degrees and minutes and seconds to enter the value

otherwise you can just covert the 41' to degrees by 41/60, since there are 60 minutes in 1 degree, so in degrees will be 18 + 41/60

and make sure your calculator is in Degree mode as well