Google Maps API Rectangle

I'm building a web app that makes use of the Google Maps API and have run across a small math problem.

I have a ce开发者_运维知识库nter point in lat/lng and an area in kilometres. How would I calculate the NE and SW lat/lng points for a bounding box? Thanks.

Consider using methods of Projection class http://code.google.com/apis/maps/documentation/javascript/reference.html#Projection to convert values from latang format to km and back.

I can suggest the following algo:

1. Convert center point to km.
2. Subtract a half of rectangle's width from x coord.
3. Subtract a half of rectangle's height from y coord.
4. Add a half of rectangle's width to x coord.
5. Add a half of rectangle's height to y coord.
6. You have two points now, just convert them to latlng.