Ever tried to draw a circle on a Google Map ? You can't do it, as you might expect, by quoting a centre point and a radius and saying "draw circle". Google Maps only draws straight lines To draw a circle you have to construct a polygon. And for a polygon to look like a circle you need at least 40 vertices, each of which needs a latitude and longitude. This will take a very long time to figure out and code.

Fortunately there are some smart people out there who figured out how to make the PC do all the hard work. Not only that, they shared it with the rest of the world.

Thanks guys !

The map is centered on Bursledon Brickworks in south Hampshire (UK). The outer (green) circle is 15 miles radius and has 100 vertices (points). The blue circle is 10 miles radius and has 40 points and the red circle is 5 miles radius also with 40 points.