We have a triangle where.
a=adjacent leg of A=30 ft
A=90º-(angle of depression)=90º-10º=80º
b=distance between the base of the lighthouse and the ship
tan A= opposite /adjacent.
tan 80º=b /30 ft ⇒b=(30 ft)(tan 80º)≈170.14 ft
Answer: the distance would be 170.14 ft
