Find area of triangle (three sides) using hero formula ( java & example)

• Given three sides of triangle, find the area of triangle using hero’s formula.
• Suppose a, b and c are the sides of triangle.
• We will read the input from console using Scanner class.

1. Algorithm: find area of triangle using hero’s formula in java (example)

1. Read the sides of triangle from console.
2. Check given sides of triangle can form a valid triangle.
   • Any two sides of a triangle should be greater than third side.
   • If yes, We will find out the area of triangle.
3. Find the semi perimeter of triangle.
   •  semiPerimeter = (a+ b + c)/2
4. Find out the area of triangle using semi perimeter
   • Area = sqrt(s(s-a)(s-b)(s-c))

2. Program: calculate area of triangle using hero formula in java (example)

package org.learn;

import java.util.Scanner;

public class AreaOfTriangleHero {

 public static void main(String[] args) {
  try (Scanner scanner = new Scanner(System.in)) {
   System.out.printf("Enter length of first side of triangle : ");
   double side1 = scanner.nextDouble();  
   
   System.out.printf("Enter length of second side of triangle : ");
   double side2 = scanner.nextDouble(); 
   
   System.out.printf("Enter length of third side of triangle : ");
   double side3 = scanner.nextDouble();  
    
   boolean isValidTriangle = (side1 + side2) > side3 && (side1 + side3) > side2 &&
            (side1 + side3) > side2;
   if(!isValidTriangle) {
    System.out.println("Side of triangle are invalid");
    return;
   }
   //semiPerimeter s = (a+b+c) / 2 
   //where a,b,c are sides of triangle
   double semiPerimeter = (side1 + side2 + side3)/2;   
   //Area = sqrt(s(s-a)(s-b)(s-c))
   double area =  Math.sqrt(semiPerimeter*(semiPerimeter-side1)
         *(semiPerimeter-side2)*(semiPerimeter-side3));
   System.out.printf("Area of triangle is : %4.2f",area);
  }
 }
}

3. Output: Area of triangle using hero’s formula in java (example).

1. Enter length of first side of triangle : 5
2. Enter length of second side of triangle : 6
3. Enter length of third side of triangle : 12
4. Sides of triangle are invalid

1. Enter length of first side of triangle : 4
2. Enter length of second side of triangle : 8
3. Enter length of third side of triangle : 10
4. Area of triangle is : 15.20

1. Enter length of first side of triangle : 5
2. Enter length of second side of triangle : 7
3. Enter length of third side of triangle : 10
4. Area of triangle is : 16.25