Question
If a ship's flag is 36' above sea level, could it be seen by someone in a building 100' high that was 18 miles away? (please show work)
Yes it is visible. The ship and building are separated by a subtended angle of A = 0.2604 degrees. Between sea level points at each location, the spherical surface of the Earth rises
R (1 - cos A/2) = 0.0102 miles = 54 feet. The is not high enough to block the line of sight between points 100 and 36 feet above sea level. (But it comes close.
Yes it is visible. The ship and building are separated by a subtended angle of A = 0.2604 degrees. Between sea level points at each location, the spherical surface of the Earth rises
R (1 - cos A/2) = 0.0102 miles = 54 feet. The is not high enough to block the line of sight between points 100 and 36 feet above sea level. (But it comes close.