static void Main(string[] args) { List <Vector3> points = new List <Vector3>() { new Vector3(-8623, 0, -11289), new Vector3(11808, 0, -11289), new Vector3(11808, 0, 5688), new Vector3(-8623, 0, 5688), new Vector3(-8623, 0, 5688), }; Vector3 checkP = new Vector3(-5836, 600, 1031); Console.WriteLine(Geometric.IsPointInArea(points.ToArray(), checkP)); }