Das erste Programm

01 Pythagoras/01 Pythagoras.csproj

+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <RootNamespace>_01_Pythagoras</RootNamespace>
+  </PropertyGroup>
+
+</Project>

01 Pythagoras/Program.cs

+using System;
+
+namespace _01_Pythagoras
+{
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            double a, b, c;
+            Console.WriteLine("Pythagoras");
+
+            Console.Write("Länge der Seite a: ");
+            a = Convert.ToDouble(Console.ReadLine());
+
+            Console.Write("Länge der Seite b: ");
+            b = Convert.ToDouble(Console.ReadLine());
+
+            Console.WriteLine($"Länge der Seite c: {Math.Sqrt(a * a + b * b)}");
+        }
+    }
+}

Prog1_WS2021_22.sln

@@ -3,7 +3,19 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 16
 VisualStudioVersion = 16.0.31702.278
 MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "01 Pythagoras", "01 Pythagoras\01 Pythagoras.csproj", "{8DC7B6AA-65FE-46EA-B91C-245660F723E8}"
+EndProject
 Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{8DC7B6AA-65FE-46EA-B91C-245660F723E8}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{8DC7B6AA-65FE-46EA-B91C-245660F723E8}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{8DC7B6AA-65FE-46EA-B91C-245660F723E8}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{8DC7B6AA-65FE-46EA-B91C-245660F723E8}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection