# How to Calculate Area of Triangle in Java

Area of any type of triangle can be calculated using the formula, **Area = (b*h)/2**, where b is the base of the triangle and h is the vertical height. The following diagram shows how to define base and vertical height of a triangle.

The following sample Java program calculates the area of a triangle given its base and vertical height. Note that this approach works for any triangle.

import java.util.Scanner; /** * Calculates area of triangle in Java given its base and vertical height. * @author jj */ public class AreaOfTriangle1 { public static void main(String[] args) { Scanner sn = new Scanner(System.in); System.out.println("Enter base of triangle:"); double base = sn.nextDouble(); System.out.println("Enter vertical height of triangle:"); double verticalHeight = sn.nextDouble(); AreaOfTriangle1 at = new AreaOfTriangle1(); double area = at.calculateArea(base,verticalHeight); System.out.println("Area = "+area); } /** * Calculates area of a triangle using base and vertical height * @param base * @param verticalHeight * @return */ private double calculateArea(double base, double verticalHeight) { return base*verticalHeight/2; } }

However if you don't know base and vertical height, you can also calculate area of a triangle using Heron's formula. This requires the length of all three sides of the triangle. According to heron's formula, the area of a triangle with 3 sides a, b and c is,

**Area = square root of (p*(p-a)*(p-b)*(p-c))** (where p = (a+b+c)/2).

The following sample Java program calculates the area of a triangle given the length of its 3 sides. The following Java program also checks whether the given 3 sides can form part of a triangle. For a triangle, the sum of its 2 sides will always be greater than the third side.

import java.util.Scanner; /** * Calculates area of triangle in Java given its 3 sides. * @author jj */ public class AreaOfTriangle2 { public static void main(String[] args) { Scanner sn = new Scanner(System.in); System.out.println("Enter length of first side of triangle:"); double a = sn.nextDouble(); System.out.println("Enter length of second side of triangle:"); double b = sn.nextDouble(); System.out.println("Enter length of third side of triangle:"); double c = sn.nextDouble(); AreaOfTriangle2 at = new AreaOfTriangle2(); if(at.isTriangleValid(a, b, c)) { double area = at.calculateArea(a,b,c); System.out.println("Area = "+area); }else { System.out.println("Sides entered cannot form a triangle!"); } } /** * Calculates area of a triangle using length of its 3 sides */ private double calculateArea(double a, double b, double c) { double p = (a+b+c)/2; return Math.sqrt(p*(p-a)*(p-b)*(p-c)); } /** * Checks whether the 3 sides can form a triangle * The sum of any two sides must be greater than the other side * @param a * @param b * @param c * @return */ private boolean isTriangleValid(double a, double b, double c) { if((a+b)>c && (a+c)>b && (b+c)>a) { return true; }else { return false; } } }