Let's take a closer look at eratosthenes' calculation of the circumference of the earth. we could repeat the measurement here in east lansing and somewhere due north between here and mackinac city.
1. suppose we travel 230 km north (as the crow flies). since we know the correct answer for the circumference of the earth- -40,008 km--what is the difference in the angle of the shadows we would see at the same day and time in these two different locations?