How to detect if a point is in a Circle?
Use the spherical geometry library (be sure to include it with the API)
function pointInCircle(point, radius, center)
{
return (google.maps.geometry.spherical.computeDistanceBetween(point, center) <= radius)
}
You could just do the distance comparison manually, fairly trivially.
(x1 - x2)^2 + (y1 - y2)^2 <= D^2