added things

Algorithms/TrigonometryUtil.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace Algorithms;
+
+
+class TrigonometryUtil {
+
+    public static double Side(double hypothenuse, double otherSide){
+        return Math.Sqrt(hypothenuse * hypothenuse  -  otherSide * otherSide);
+    }
+
+    public static double Hypothenuse(double a, double b){
+        return Math.Sqrt(a * a + b * b);
+    }
+
+    public static double Area(double hypothenuse, double side){
+        double otherSide = Side(hypothenuse, side);
+        return side * otherSide * 0.5;
+    }
+}