adding project for pythagore theorem

C# Full Course for free/7.hypotenuse_calculator.md

@@ -4,5 +4,17 @@ in this project we will cover how to implement
 the hypotenuse theorem
 
 $$
-a^2 + b^2 = c^2
+\sqrt{a^2 + b^2} = c
 $$
+
+```C#
+Console.Write("enter the length of A :");
+double a = Convert.ToDouble(Console.ReadLine());
+
+Console.Write("enter the length of B :");
+double b = Convert.ToDouble(Console.ReadLine());
+
+c = Math.Sqrt(Math.Pow(a,2) + Math.Pow(b,2))
+
+Console.WriteLine("C is equal to : " + c);
+```