In this tutorial, we will show you how to calculate the distance between two locations geolocated by using latitude and longitude in Python. This distance calculation uses the **Spherical Law of Cosines**, which uses trigonometry to measure the curvature of the earth, to accurately measure the distances on the Earth.

```
import math
def distance(lat1, lon1, lat2, lon2, unit):
if (lat1 == lat2) and (lon1 == lon2):
return 0
else:
theta = lon1-lon2
dist = math.sin(math.radians(lat1)) * math.sin(math.radians(lat2)) + math.cos(math.radians(lat1)) * math.cos(math.radians(lat2)) * math.cos(math.radians(theta))
dist = math.acos(dist)
dist = math.degrees(dist)
miles = dist * 60 * 1.1515;
unit = unit.upper()
if unit == 'K':
return miles * 1.609344
elif unit == 'N':
return miles * 0.8684
else:
return miles
print(str(distance(32.9697, -96.80322, 29.46786, -98.53506, "M")) + " Miles")
print(str(distance(32.9697, -96.80322, 29.46786, -98.53506, "K")) + " Kilometer")
print(str(distance(32.9697, -96.80322, 29.46786, -98.53506, "N")) + " Nautical Miles")
```

The code above creates the function named **distance **to calculate the distance between two locations. It implies the simple spherical law of cosines that gives well-conditioned results down to distances as small as a few meters on the Earth’s surface. The distance function makes use of the spherical law of cosines formula `cos `

and derived into the distance calculation.*c* = cos *a* cos *b* + sin *a* sin *b* cos *C*

Parameters that are passed to the distance function are:**lat1**, **lon1** = Latitude and Longitude of point 1 in decimal degrees**lat2**, **lon2 **= Latitude and Longitude of point 2 in decimal degrees**unit **= the unit you desire for results where ‘M’ is the statute miles (default), ‘K’ is kilometers and ‘N’ is nautical miles