In the previous article, we have seen Java Program to Find Area of Enneagon

In this article we are going to see how to find the area of octagon using Java programming language.

## Java Program to Find Area of Octagon

Before Jumping into the program directly let’s see how we can find the area of octagon.

**Explanation:**

Regular octagon is a closed figure having 8 sides of equal length and equal internal triangle. Formula to find area of octagon (approx.) = 2(1+√2)*s*s where 's' represents side length of octagon i.e Area = 2 × (side length of octagon)² × (1+sqrt(2))

**Example: **

Let one of the sides of octagon be “s” = 1 So, vol. of octagon = 2(1+√2)*s*s = = 2(1+√2)*1*1 = = 2(1+√2) = 4.8284

Let’s see different ways to find area of octagon.

### Method-1: Java Program to Find Area of Octagon By Using Static Value

**Approach:**

- Declare an double variable say “
`s`

”, assign the value to it, which holds the value for one of the side of octagon. - Find the surface area of octagon using the formula
`2(1+√2)*s*s`

- Print the result.

**Program:**

import java.io.*; class Main { public static void main(String [] args) { //side length of octagon declared double s = 1; //finding area using formula double area = 2*(1+Math.sqrt(2))*s*s; System.out.println("The area of octagon is: " + area); } }

Output: The area of octagon is: 4.82842712474619

### Method-2: Java Program to Find Area of Octagon By Using User Input Value

**Approach:**

- Declare an integer variable say “
`s`

”, assign the value to it, which holds the value for one of the side of octagon. - Find the surface area of octagon using the formula
`2(1+√2)*s*s`

- Print the result.

**Program:**

import java.util.*; class Main { public static void main(String [] args) { //Scanner class object created Scanner sc = new Scanner(System.in); //Taking input of side length System.out.println("Enter the value of one side of the octagon:"); double s = sc.nextInt(); //finding area using formula double area = 2*(1+Math.sqrt(2))*s*s; System.out.println("The area of octagon is: " + area); } }

Output: Enter the value of one side of the octagon: 2 The area of octagon is: 19.31370849898476

### Method-3: Java Program to Find Area of Octagon By Using User Defined Method

**Approach:**

- Declare an integer variable say “
`s`

”, assign the value to it, which holds the value for one of the side of octagon. - Call the user defined method say
`findArea()`

and pass the side length i.e. ‘`s`

‘ as parameter. - Inside the method find the surface area of octagon using the formula
`2(1+√2)*s*s`

- Print the result.

**Program:**

import java.util.*; class Main { public static void main(String [] args) { //Scanner class object created Scanner sc = new Scanner(System.in); //Taking input of side length System.out.println("Enter the value of one side of the octagon:"); double s = sc.nextInt(); //calling the findArea() method findArea(s); } public static void findArea(double s) { //finding area using formula double area = 2*(1+Math.sqrt(2))*s*s; System.out.println("The area of octagon is: " + area); } }

Output: Enter the value of one side of the octagon: 4 The area of octagon is: 77.25483399593904

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