**C. 981.** The captain of a ship wrote down the formula in his log book for the distance to the horizon. Unfortunately, the number *p* got blurred. *d* denotes the distance to the horizon in kilometers, and *h* stands for the height of the eyes of the observer above sea level in metres. Determine a value of *p* that provides a practicable formula. (Use 6370 km for the radius of the Earth.)

(5 points)

**Deadline expired on 15 April 2009.**