public static double GetResult(GeometryBasicsDistanceBetweenCirclesIn2D.Circle a,
                                           GeometryBasicsDistanceBetweenCirclesIn2D.Circle b)
            {
                var distanceDiff =
                    Math.Sqrt(Math.Pow(a.Center.X - b.Center.X, 2) + Math.Pow(a.Center.Y - b.Center.Y, 2)) - a.Radius -
                    b.Radius;

                return(distanceDiff > 0 ? distanceDiff : 0);
            }
        public void RandomTests()
        {
            Random rand = new Random();

            for (int i = 0; i < 100; i++)
            {
                GeometryBasicsDistanceBetweenCirclesIn2D.Circle a =
                    new GeometryBasicsDistanceBetweenCirclesIn2D.Circle(
                        new Point(rand.Next(-50, 50), rand.Next(-50, 50)), rand.Next(1, 50));
                GeometryBasicsDistanceBetweenCirclesIn2D.Circle b =
                    new GeometryBasicsDistanceBetweenCirclesIn2D.Circle(
                        new Point(rand.Next(-50, 50), rand.Next(-50, 50)), rand.Next(1, 50));
                Assert.AreEqual(Math.Round(Solve.GetResult(a, b), 6),
                                Math.Round(GeometryBasicsDistanceBetweenCirclesIn2D.DistanceBetweenCircles(a, b), 6));
            }
        }