Appropriate Level: Trigonometry
The Story: I spent a summer in Chicago and early one morning I watched the sun rise over Lake Michigan (the lake is large enough that you cannot see across it, at least from Chicago). I stood at the waters edge and waited for the first rays of sunlight to peak over the water. When that happened I immediately laid down on the sand near the waters edge, and could no longer see the sun. It took about 10 seconds before the “first” rays of sun were again visible. By the way, when I am standing, my eyes are roughly 5 ft above the ground.
The Question: What is the radius of the earth?