Final answer:
The question is related to the use of trigonometric functions for calculating positions in navigation, which is part of Mathematics, and it would be typically taught at the High School level.
Step-by-step explanation:
The question regarding a ship sighting a lighthouse at an angle of 15° is related to trigonometric functions which fall under the subject of Mathematics. Specifically, this scenario pertains to topics such as angles, navigation, and potentially vector subtraction if direction and movement are involved. In mathematical terms, one might use trigonometric functions such as sine, cosine, or tangent to calculate distances or relative positions in navigation. Knowing the angle and distance from the lighthouse, a navigator could determine the ship's exact position along a parallel to shore.
Historically, sailors would use the position of celestial bodies like the Sun to determine their latitude at sea. This required understanding and applying certain angles and navigation tables to personalize the data to their specific date and time. Today, sailors continue to rely on principles of trigonometry for accurate navigation, though they are often assisted by modern GPS technology.