Add Perimeter Calculation Algorithms (#3247)

Co-authored-by: Andrii Siriak <siryaka@gmail.com>

src/main/java/com/thealgorithms/maths/Perimeter.java

@@ -0,0 +1,38 @@
+package com.thealgorithms.maths;
+
+public class Perimeter {
+    public static void main(String[] args) {
+        System.out.println(perimeter_polygon(5,4));
+        System.out.println(perimeter_rectangle(3,4));
+        System.out.printf("%,3f",circumference(5));
+    }
+    // Perimeter of different 2D geometrical shapes
+    /**
+     *Calculate the Perimeter of polygon.
+     * @parameter length of side.
+     * @parameter number of sides.
+     * @return Perimeter of given polygon
+     */
+    public static float perimeter_polygon( int n, float side){
+        float perimeter = n*side;
+        return perimeter;
+    }
+    /**
+     *Calculate the Perimeter of rectangle.
+     * @parameter length and breadth.
+     * @return Perimeter of given rectangle
+     */
+    public static float perimeter_rectangle( float length, float breadth){
+        float perimeter = 2*(length + breadth);
+        return perimeter;
+    }
+    /**
+     *Calculate the circumference of circle.
+     * @parameter radius of circle.
+     * @return circumference of given circle.
+     */
+    public static double circumference( float r){
+        double circumference = 2*Math.PI*r;
+        return circumference;
+    }
+}

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

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+package com.thealgorithms.maths;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class perimeterTest {
+
+    //Perimeter of polygon
+    @Test
+    void testcase1(){
+        Assertions.assertEquals(20.0,Perimeter.perimeter_polygon(4,5));
+    }
+    @Test
+    void testcase2(){
+        Assertions.assertEquals(30.0,Perimeter.perimeter_polygon(5,6));
+    }
+
+    //Perimeter of Rectangle
+    @Test
+    void testcase3(){
+        Assertions.assertEquals(18.0,Perimeter.perimeter_rectangle(4,5));
+    }
+    @Test
+    void testcase4(){
+        Assertions.assertEquals(14.0,Perimeter.perimeter_rectangle(4,3));
+    }
+
+    //Circumference of a circle
+    @Test
+    void testcase5(){
+        Assertions.assertEquals(31.41592653589793,Perimeter.circumference(5));
+    }
+    @Test
+    void testcase6(){
+        Assertions.assertEquals(43.982297150257104,Perimeter.circumference(7));
+    }
+}