Надявам се да е полезно :)
using System; class PointInACircle { static void Main() { double pointX = double.Parse(Console.ReadLine()); double pointY = double.Parse(Console.ReadLine()); double circleX = 0; double circleY = 0; double radius = 2; bool isInCircle = false; double distance = Math.Sqrt(Math.Pow(pointX - 0, 2) + Math.Pow(pointY - 0, 2)); if ((Math.Abs(pointX - circleX)) * (Math.Abs(pointX - circleX)) + (Math.Abs(pointY - circleY)) * (Math.Abs(pointY - circleY)) <= radius * radius) { isInCircle = true; } if (isInCircle) { Console.WriteLine("yes {0:F2}",distance); } else { Console.WriteLine("no {0:F2}",distance); } } }