(Geometry: area of a pentagon) Write a
The formula for computing the area of a pentagon is
Geometry: Area of the pentagon
Program Plan:
- Import required packages.
- Declare the main class method “pentagon”.
- In the main method.
- Create an object “in1” for the scanner class.
- Get length from the user.
- Declare the required variables for area of pentagon.
- Calculate the area of the pentagon.
- Display the pentagon.
- In the main method.
The below program reads length and display the area of the pentagon.
Explanation of Solution
Program:
//import the required header files
import java.util.Scanner;
//create a class "pentagon"
public class pentagon
{
//main function
public static void main(String[] args)
{
//Create an object
Scanner in1 = new Scanner(System.in);
//Get length from user
System.out.print("Enter the length from the center to a vertex: ");
//Get the length in "double" type
double r1 = in1.nextDouble();
//Calculate "s1"
double s1 = 2 * r1 * Math.sin(Math.PI / 5);
//Calculate "a1"
double a1 = 5 * s1 * s1 / (4 * Math.tan(Math.PI / 5));
//Display "area"
System.out.println("The area of the pentagon is " +
Math.round(a1 * 100) / 100.0);
}
}
Enter the length from the center to a vertex: 5.5
The area of the pentagon is 71.92
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