Define an interface which has methods area(), volume(). Define constant PI. Create a class cylinder which implements this interface and calculate area and volume. (Use define())

<?php

                        interface Cyl

        {

                        function area();

                        function volume();

        }

                        class Cylinder implements Cyl

        {

                                    public $PI=3.14;

                                    public $a;

                                    public $r;

                                    public $h;

                                    function __construct($r,$h)

           {

                $this->r=$r;

                $this->h=$h;

           }

                                    function area()

           {

                $this->a=2*$this->PI*($this->h*$this->r);

                                                echo"Area of Cylinder= ".$this->a."<br>";

            }

                                    function volume()

           {

                $this->a=$this->PI*$this->r*$this->r*$this->h;

                                                echo"Volume of Cylinder= ".$this->a."<br>";

            }

        }

       $c=new Cylinder(10,7);

       $c->area();

       $c->volume();

?>