EX3.2.py

# (Geometry: great circle distance) The great circle distance is the distance between
# two points on the surface of a sphere. Let (x1, y1) and (x2, y2) be the geographical
# latitude and longitude of two points. The great circle distance between the two
# points can be computed using the following formula:
# Write a program that prompts the user to enter the latitude and longitude of two
# points on the earth in degrees and displays its great circle distance. The average
# earth radius is 6,371.01 km. Note that you need to convert the degrees into radians
# using the math.radians function since the Python trigonometric functions use
# radians. The latitude and longitude degrees in the formula are for north and west.
# Use negative to indicate south and east degrees.
import math

EARTH_RADIUS = 6371.01
x1, y1 = eval(input("Enter point 1 (latitude and longitude) in degrees:\n"))
x2, y2 = eval(input("Enter point 2 (latitude and longitude) in degrees:\n"))

x1 = math.radians(x1)
y1 = math.radians(y1)
x2 = math.radians(x2)
y2 = math.radians(y2)

d = EARTH_RADIUS * math.acos(math.sin(x1) * math.sin(x2) + math.cos(x1) * math.cos(x2)
                             * math.cos(y1 - y2))
print("The distance between the two points is", d, "km")