# Earth Distances

Simple
English

To describe a specific position on the surface of the Earth, we must rely on the geographic coordinate system. The geographic coordinate system is a method used to give every possible location on Earth to be specified by a set of numbers or letters. A common choice of coordinates is latitude and longitude. With this information we can calculate a distance between two points along a surface.

For simplicity’s sake, we will suppose that the Earth is a perfect sphere with a radius of 6,371 kilometers (it gives a mistake no more than 0.3%). You are given two point coordinates and you must find the shortest distance between these points on the surface of the Earth, measured along the surface of the Earth.

Coordinates are given as a string with the latitude and longitude separated by comma and/or whitespace. Latitude and longitude are represented in the follow format:

```    d°m′s″X
```

In this example, "d" is degrees, "m" is minutes, "s" is seconds as integers, while "X" is "N" (north) or "S" (south) for a latitude and "W" (west) or "E" (east) for a longitude.

The result should be given as a number in kilometers with a precision of ±0.1 (100 metres).

Input: Two arguments. Coordinates as strings (unicode).

Output: The distance as a number (int or float).

Example:

```distance(u"51°28′48″N 0°0′0″E", u"46°12′0″N, 6°9′0″E") == 739.2
distance(u"90°0′0″N 0°0′0″E", u"90°0′0″S, 0°0′0″W") == 20015.1```

How it is used: The concepts presented in this mission are the exact sorts of concepts used in navigational software, enabling a ship or plane to understand where it is, where it must go and how far it has gone. Along the same vein, Global Positioning Satellites use similar principles to provide pinpoint accurate locations to GPS receivers for use in navigation.

Precondition: Correct Coordinates.

45
Settings
Code:
Other:
Invalid hot key. Each hot key should be unique and valid
Hot keys:
•  to Run Code: to Check Solution: to Stop:
CheckiO Extensions

CheckiO Extensions allow you to use local files to solve missions. More info in a blog post.

In order to install CheckiO client you'll need installed Python (version at least 3.8)

Install CheckiO Client first:

`pip3 install checkio_client`

`checkio --domain=py config --key=`

Sync solutions into your local folder

`checkio sync`

(in beta testing) Launch local server so your browser can use it and sync solution between local file end extension on the fly. (doesn't work for safari)

`checkio serv -d`

Alternatevly, you can install Chrome extension or FF addon

`checkio install-plugin`
`checkio install-plugin --ff`
`checkio install-plugin --chromium`

Read more here about other functionality that the checkio client provides. Feel free to submit an issue in case of any difficulties.

Pair Programming (Beta-version)

Welcome to Pair Programming! Engage in real-time collaboration on coding projects by starting a session and sharing the provided unique URL with friends or colleagues. This feature is perfect for joint project development, debugging, or learning new skills together. Simply click 'Start Session' to begin your collaborative coding journey!

Waiting for Pair Programming to start...

You are trying to join a pair programming session that has not started yet.

Please wait for the session creator to join.

Waiting for Pair Programming to reconnect...

It looks like the creator of the pair programming session closed the editor window.

It might happen accidentally, so that you can wait for reconnection.