Add Euclidean Distance Formula (#3047)

src/test/java/com/thealgorithms/maths/DistanceFormulaTest.java

@@ -0,0 +1,28 @@
+package com.thealgorithms.maths;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class DistanceFormulaTest
+{
+  @Test
+  void test1()
+  {
+    Assertions.assertEquals(DistanceFormula.distance(1,1,2,2), 1.4142135623730951);
+  }
+  @Test
+  void test2()
+  {
+    Assertions.assertEquals(DistanceFormula.distance(1,3,8,0), 7.0710678118654755);
+  }
+  @Test
+  void test3()
+  {
+    Assertions.assertEquals(DistanceFormula.distance(2.4,9.1,55.1,100), 110.91911467371168);
+  }
+  @Test
+  void test4()
+  {
+    Assertions.assertEquals(DistanceFormula.distance(1000,13,20000,84), 19022.067605809836);
+  }
+}