Eratosthenes measured the circumference of the Earth by noting that the Sun is at an angle of 7°12' = 7.2° ("one-fiftieth of a circle") south of the vertical in Alexandria at the same time of day and year that it is directly overhead in Syene. Syene is 5000 stades directly south of Alexandria. (The stade was a Mediterranean unit of length that varied slightly from region to region, but in Egypt was most likely equal to 157.5 meters.) Find the circumference of the Earth from these data. The Earth's equitorial circumference is 40075 km according to NASA. What was Eratosthenes percent error?