**Java Basic Program**

➤ Hello World program

➤ Java Addition Program

➤ Average of 2 Numbers

➤ Average of 3 Numbers

➤ Simple Interest in Java

➤ Compound Interest

➤ Display ASCII Value

➤ Area of Circle Java

➤ Area of Rectangle

➤ Java Area of Triangle

➤ Java Swap 2 Numbers

➤ Distance b/w 2 Points

**Java Flow Control Program**

**Java Array Programs**

**Java String Programs**

In this tutorial, we will develop a Java program to find the area of a triangle. Generally, we find the area of a triangle having three sides, or the area of the right-angle triangle.

**Program to find the area of the right-angle triangle in Java**

Area of Right angle triangle or Triangle whose base and height is known, their area is given by,

**Area=(1/2) * base * height **

Procedure to develop a program to find the area of a right-angle triangle:-

1) Define class and the main method

2) Declare variables for taking inputs:- height and length

3) Import Scanner class of util package to read inputs

4) Read inputs from end-user and store them in the declared variables

5) Calculate the area of the right angle triangle using the formula, and store it in a variable

6) Display the result

7) Close the Scanner class object

```
import java.util.Scanner;
public class RightAngleTraingle {
public static void main(String[] args) {
// declare variables
double height = 0.0;
double base = 0.0;
double area = 0.0;
// create Scanner class object
Scanner scan = new Scanner(System.in);
// read input
System.out.print("Enter height of the triangle:: ");
height = scan.nextDouble();
System.out.print("Enter base of the triangle:: ");
base = scan.nextDouble();
// calculate area
area = (0.5) * (base * height);
// display result
System.out.println("Area = "+ area);
// close Scanner class object
scan.close();
}
}
```

Output:-

Enter `height`

of the triangle:: 25.5

Enter `base`

of the triangle:: 20

Area = 255.0

In this program, we had written logic to find the area of the right-angle triangle inside the main method, but we should not do that. It was given only for understanding purposes. We should write the logic inside a method and call them from the main method. In the below program we had written that logic separately in the user-defined method.

## Java program to find the area of a triangle given three sides

Triangle having three sides their area is given by Heron’s Formula for the area of a triangle. If a, b and c are sides of triangles, and s is semi-perimeter then from Heron’s Formula,

** s = (a+b+c) / 2 **

and,

**area = √(s*(s-a)*(s-b)*(s-c))**

To find the square root value we can take the support of ** sqrt()** method of Math class. The sqrt() method of Math class is a static method so we can call it without creating the object of Math class.

```
import java.util.Scanner;
public class RightAngleTraingle {
public static double findTriangleArea(double a, double b, double c){
double s = 0.0;
double area = 0.0;
s = (a+b+c) / 2;
area = Math.sqrt( s* (s-a) * (s-b) * (s-c) );
return area;
}
public static void main(String[] args) {
// declare variables
double a = 0.0, b = 0.0, c = 0.0;
double area = 0.0;
// create Scanner class object
Scanner scan = new Scanner(System.in);
// read input
System.out.print("Enter three sides of the triangle:: ");
a = scan.nextDouble();
b = scan.nextDouble();
c = scan.nextDouble();
// call method to calculate area
area = findTriangleArea(a, b, c);
// display result
System.out.println("Area = "+ area);
// close Scanner class object
scan.close();
}
}
```

Output for the different test-cases:-

Enter three sides of the triangle:: 4.5 8.9 12

Area = 16.643689494820542

Enter three sides of the triangle:: 3 4 5

Area = 6.0

Here we developed a java program to find the area of a triangle using methods. We define findTriangleArea(-,-,-) which takes three double type arguments and also returns double type value.

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