How Android calculates distance from latitude and longitude

Query the SQL statement for map points that are less than 10 kilometers long.

result = mysql_query ( "select name,longitude,latitude,des from location

where type=".$type." and ((longitude - ".$lng.") *longitude - ".$lng.") +latitude

$lat.") *latitude - ".$lat.")) = (10 / 110) *10 / 110))");

The core part of it is ((longitude -".$lng.") *longitude - ".$lng.") +latitude -

lat.") *latitude - ".$lat.")) = (10 110) *10 110)), lng and $lat respectively**.

Latitude and longitude submitted from the Android client.

Calculation formula:

1. LAT1 LUNG1 represents the latitude and longitude of point A, and LAT2 LUNG2 represents the latitude and longitude of point B;

2. a=lat1 lat2 is the difference between two points of latitude b=lung1 -lung2 is the difference between two points of longitude;

3. It is the radius of the earth, and the unit is kilometers;

The calculated result is measured in kilometers.

Dear, glad to answer for you. There is a method in the Locaiont class that can directly calculate the distance between 2 points, it seems to be called distanceto() or something, just look at it in the API, or calculate it yourself, and treat the earth as a sphere. Hope it helps, hope to adopt!

There is a diagram below, which is drawn with a cylindrical projection.

111／2×（50+60）=a(km)

Count a again"b:

30×111=b(km)

Finally, the Pythagorean theorem yields ab

ab is what you want.

a=6105

b=3330

The end result is:

It's hard to calculate, but this method can be calculated.