Geographic math question

[M5]

Not being very strong at math, I have a little problem that I'm not  
sure how to solve. Maybe someone can help me.

Basically, given a point (latitude, longitude) and a radius (100  
meters) (think circle), I need to compute an equivalent square: That  
is, two points that would correspond to two corners of the square.

From:	51, -114			100 meters
To:		51.005, -114.005	NE corner
		49.995, -113.995	SW corner

Now, the above is not really accurate, of course, since the earth is  
spherical (well, at least most people think so), and I would like  
this computation to run in MySQL query, e.g.:

UPDATE places SET ne_latitude = (*), ne_longitude = (*), sw_latitude  
= (*), sw_longitude = (*)

In the above table, there are already three columns with the centre  
latitude and longitude and radius. Any ideas? Thanks.

...Rene



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