public double getDirection(Tank that) {
Coordinate other = that.getLocation();
return Math.atan2(other.y() - location.y(), other.x() - location.x());
}
public double getDistance(Tank that) {
Coordinate other = that.getLocation();
return Math.sqrt(Math.pow(other.x() - location.x(), 2) + Math.pow(other.x() - location.y(), 2));
}