CheckPointInCircle1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CheckPointInCircle1
(
class CheckPointInCircle1
    {
        static void Main()
        {
            //(x-a)^2 + (y-b)^2 = r^2
            //x^2 == x*x
            //We need first part to be equal or small than the second,
            //becouse we looking for a point IN the circle.
            //The points on the perimeter of the circle ARE in it!

            double radiusR = 5;
            double circleX = 0;
            double circleY = 0;

            Console.WriteLine(@"Checking if given point (x,  y) is within a circle K(O, 5)...");

            Console.Write(@"Please Provide ""x"": ");
            double pointX = double.Parse(Console.ReadLine());

            Console.Write(@"Please Provide ""y"": ");
            double pointY = double.Parse(Console.ReadLine());

            double checkX = (pointX - circleX) * (pointX - circleX); //(x-a)^2
            double checkY = (pointY - circleY) * (pointY - circleY); //(y-b)^2
            double xyCheck = (checkX + checkY);                      //(x-a)^2 + (y-b)^2
            double rCheck = (radiusR * radiusR);                     //r^2

            if (xyCheck <= rCheck)
                {
                    Console.WriteLine("The pоint IS in the circle!");
                }
            else
                {
                    Console.WriteLine("The point IS NOT in the circle!");
                }
        }
    }
}