Answer:
Step-by-step explanation:
Please see attached photo for explanation. 
In the attached photo, X is the distance of the swimmer from the cliff. 
Thus, we can obtain the value of x by using Tan ratio as illustrated below:
θ = 54.6°
Opposite = 100 foot 
Adjacent = x =.? 
Tan θ = Opposite /Adjacent
Tan 54.6 = 100/x
Cross multiply 
x × Tan 54.6 = 100
Divide both side by Tan 54.6
x = 100 / Tan 54.6
x = 71.07 foot 
Therefore, the swimmer is 71.07 foot from the cliff.