Java: Calculate the area of a triangle

Last update on May 14 2025 13:03:07 (UTC/GMT +8 hours)

Calculate Triangle Area

Write Java methods to calculate triangle area.

Pictorial Presentation:

Sample Solution:

Java Code:

import java.util.Scanner;
public class Exercise13 {
  public static void main(String[] args)
    {
        Scanner in = new Scanner(System.in);
         System.out.print("Input Side-1: ");
         double side1 = in.nextDouble();
         System.out.print("Input Side-2: ");
         double side2 = in.nextDouble();
         System.out.print("Input Side-3: ");
         double side3 = in.nextDouble();
         System.out.println( is_Valid(side1, side2,side3) ?
                "The area of the triangle is " + area_triangle(side1, side2, side3) : "Invalid triangle" );
    }

  public static boolean is_Valid(double side1, double side2, double side3) {
        if( side1 + side2 > side3 &&
                side2 + side3 > side1 &&
                side1 + side3 > side2) return true;
        else return false;
    }
   public static double area_triangle(double side1, double side2, double side3) {
        double area = 0;
        double s = (side1 + side2 + side3)/2;
        area = Math.sqrt(s*(s - side1)*(s - side2)*(s - side3));
        return area;
    }
}

Sample Output:

Input Side-1: 10                                                                                              
Input Side-2: 15                                                                                              
Input Side-3: 20                                                                                              
The area of the triangle is 72.61843774138907 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to calculate the area of a triangle using Heron’s formula given its three side lengths.
• Write a Java program to compute the area of a right triangle using base and height inputs.
• Write a Java program to calculate the area of a triangle using the sine of an angle given two sides and the included angle.
• Write a Java program to compute the area of an equilateral triangle given its side length.

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