code: func (t T) Offset(origin kml.Coordinate, distance, bearing float64) kml.Coordinate {
  	lat := math.Asin(math.Sin(origin.Lat*radians)*math.Cos(distance/t.R) + math.Cos(origin.Lat*radians)*math.Sin(distance/t.R)*math.Cos(bearing*radians))
  	lon := origin.Lon*radians + math.Atan2(math.Sin(bearing*radians)*math.Sin(distance/t.R)*math.Cos(origin.Lat*radians), math.Cos(distance/t.R)-math.Sin(origin.Lat*radians)*math.Sin(lat))
  	return kml.Coordinate{
  		Lon: lon * degrees,
  		Lat: lat * degrees,
  		Alt: origin.Alt,
  	}
  }
docs: // Offset returns the coordinate at distance from origin in direction bearing.