feat: Add Circle class with methods for area, perimeter, and circumference

WHAT the code does:
Defines a Circle class with:
- radius field representing the circle’s size.
- area(): computes area using πr².
- perimeter(): computes perimeter, though currently using 2 * π * r² instead of the standard 2πr.
- circumferenec(): calls perimeter() to return the same value.
Defines AreaandPerimeter with main():
- Creates two Circle objects (radii 7 and 14).
- Prints area, perimeter, and circumference for each.

WHY this matters:
Demonstrates class-based modeling of geometric entities.
Shows how methods encapsulate formulas for properties of a circle.
Illustrates reusability: multiple Circle objects use the same logic with different radii.
Highlights object-oriented principles: data (radius) and behavior (area, perimeter) are bundled.

HOW it works:
c1 and c2 are instantiated with different radii.
Each object calls area(), perimeter(), and circumferenec().
Results are printed for both circles.

Tips and gotchas:
The formula in perimeter() is incorrect: it uses 2πr² instead of 2πr. This makes circumferenec() also return the wrong value.
circumferenec() is redundant if it just mirrors perimeter(); normally circumference is another name for perimeter.
radius is public; in real-world code, prefer private with getters/setters or constructors for better encapsulation.
Overriding toString() would simplify printing all properties at once.

Use-cases:
Educational demo of methods, object instantiation, and encapsulation of mathematical logic.
Foundation for a geometry library handling multiple shapes.
Useful for teaching class design and method reuse in beginner-level Java.

Short key: class-circle area-perimeter circumference-geometry.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section11ObjectOrientedProgramming/src/AreaandPerimeter.java

@@ -1,48 +1,42 @@
-//Area of circle and perimeter of circe.
-
-class Circle
-{
+class Circle {
     //All these are the properties of the circle class
-
     public double radius;
 
-    public double area()
-    {
-        //Formula for area. Math.PI Built in constant givem in class.
+    public double area() {
+        //Formula for area. Math.PI Built in constant given in class.
         //Predefine final here.
         return Math.PI * radius * radius;
     }
+
     //Perimeter method
-    public double perimeter()
-    {
+    public double perimeter() {
         //Formula for perimeter
         return 2 * Math.PI*radius*radius;
     }
-    //One more method
 
-    public double circumferenec()
-    {
+    //One more method
+    public double circumferenec() {
         //Calling the Perimeter method or you write the formula instead.
-
         return perimeter();
     }
 }
 
 class AreaandPerimeter{
-    public static void main(String[] args)
-    {
+    public static void main(String[] args) {
         Circle c1 = new Circle();
         Circle c2 = new Circle();
 
         c1.radius = 7;
-        c2.radius=14;
+        c2.radius = 14;
 
         System.out.println("Area: "+c1.area());
         System.out.println("Perimeter: "+c1.perimeter());
         System.out.println("Circumference: "+c1.circumferenec());
 
+        System.out.println("\n");
+
         System.out.println("Area: "+c2.area());
         System.out.println("Perimeter: "+c2.perimeter());
         System.out.println("Circumference: "+c2.circumferenec());
     }
-}
+}