Given our assumptions, we can model the problem as a right triangle with two known and one unknown sides. This is because the line of sight is tangent to the earth's surface. If you refer to the diagram, you will see that the length of the hypotenuse (the earth's radius plus Kitty Hawk's height) and one of the other sides (the earth's radius) are known, and that the length of the unknown side is exactly the line-of-sight distance that we want to determine.

Given this model, our method is clear. We will exploit the Pythagorean Theorem to solve for the unknown side in terms of the two known sides.

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Joseph L. Zachary
Hamlet Project
Department of Computer Science
University of Utah