Java Program to Find the Perimeter of a Circle

A circle is a simple shape consisting of all the points in the plane that are equidistant from a point known as the center of the circle. In this article, we will learn how to find the area of the circle.

Terminology:

• Perimeter: A quantity of measurement or boundary of the circle. It is basically the distance around a closed figure.
• Radius: The line segment from the center to any point of the circle is known as radius.
• Diameter: The line segment whose endpoints lie on the circle and passed through the center is known as the diameter of the circle. It is also known as the largest distance between any two points on the circle.

Perimeter Of A Circle:

• Using the radius of the circle:

Formula:

Perimeter of the circle:  P =2 *  π * r

Here, r is the radius of the circle.

• Using the diameter of the circle:

Formula:

Perimeter of the circle:  A =  π * d

Note: The value of PI in java is 3.141592653589793. 

Example 1:

Java

// Java program to find
// the perimeter of the circle
// using radius

import java.io.*;

class GFG {

    static final double PI = Math.PI;

    // Function to calculate the
    // perimeter of the circle
    static double Perimeter(double r)
    {
      return 2 * PI * r;
    }

    // Driver code
    public static void main(String[] args)
    {

        // Radius
        double r = 5;

        // Calling Perimeter function
        System.out.println("Perimeter of the circle is :"
                           + Perimeter(r));
    }
}

Output

Perimeter of the circle is :31.41592653589793

Time complexity: O(1)

Auxiliary space: O(1)

 Example 2:

Java

// Java program to find
// the area of the circle
// Using Diameter

import java.io.*;

class GFG {

    static final double PI = Math.PI;

    // Function to calculate the
    // perimeter of the circle
    // using Diameter
    static double Perimeter(double D)
    {
        return PI * D;
    }

    // Driver code
    public static void main(String[] args)
    {

        // Diameter
        double D = 20;

        // Calling Perimeter function
        System.out.println("Perimeter of the circle is :"
                           + Perimeter(D));
    }
}

Output

Perimeter of the circle is :62.83185307179586

Time complexity: O(1)

Auxiliary space: O(1)