public static void Run() { int T = int.Parse(Console.ReadLine()); for (int i = 0; i < T; i++) { Point a = Point.ReadFromConsole(); Point b = Point.ReadFromConsole(); Point c = Point.ReadFromConsole(); Point d = Point.ReadFromConsole(); Point abVector = a.Subtract(b); Point acVector = a.Subtract(c); Point adVector = a.Subtract(d); Point normalVector = abVector.CrossProduct(acVector); int crossProduct = normalVector.DotProduct(adVector); Console.WriteLine(crossProduct == 0 ? "YES" : "NO"); } }