I a lighthouse is 75 feet tall and boat is out at sea 40 min away, how far is the boaat from the lighthouse. I'm stump on this problem..Help!
By simple trigonometry on a plane:
θ=48 minutes (angle of depression)
h=75'
distance = 75/tan(48')
=75/0.01396
=5371.1 feet away
=1.02 mile approx.
If you are looking for correction for the curvature of the earth, a more complex calculation will be required.