title: Get all cities in latitude/longitude range
body: <p>I have a list of cities, each of them obviously has a longitude and latitude.</p>
  
  <p>Now selecting one of these cities, i want to obtain all the other cities that have a longitude / latitude in  a range of 50 km from the selected city.
  What formula should I use?</p>
  
  <p><strong>I am only interested in the mathematical formula to convert km to  latidutine and longitude from a know city position</strong></p>
  
  <p>Then i will calculate the maximum and minimum latitude and longitude, for considering an acceptable  range. (like a Square) </p>
  
  <p>tks</p>
  
  <hr>
  
  <p>I don't want to calculate the distance between two points!+
  I want to calculate min e max latitude and longitude and then filter my cities by this coordinates.</p>
  
  <p>I've found a sample in Php that worked for me. 
  (i've ported it to C#)</p>
  
  <p><a href="http://blog.fedecarg.com/2009/02/08/geo-proximity-search-the-haversine-equation/" rel="nofollow">http://blog.fedecarg.com/2009/02/08/geo-proximity-search-the-haversine-equation/</a></p>