Respuesta :
LetÂ
X= the altitude of the lighthouse above sea level= 80 ft A = the angle of depressionÂ
Y=Â the distance of the boat from the lighthouse= 400 ft
 tan A=X/Y------------------ > 80/400=0.2
arctan (0.2)=11.31 degree
 The answer is the angle of depression is 11 degree