Work each problem. See Example 5. Circumference of Earth The first accura...

Work each problem. See Example 5.

Circumference of Earth The first accurate estimate of the distance around Earth was done by the Greek astronomer Eratosthenes (276– 195 b.c.), who noted that the noontime position of the sun at the summer solstice in the city of Syene differed by from its noontime position in the city of Alexandria. (See the figure.) The distance between these two cities is 496 mi. Use the arc length formula to estimate the radius of Earth. Then find the circumference of Earth. (Source: Zeilik, M., Introductory Astronomy and Astrophysics, Third Edition, Saunders College Publishers.)