You can go HERE: http://www.mathopenref.com/coordtrianglearea.html and use the formula described there:

**and here's my solution:**

import java.util.Scanner;
public class Pr_02_TriangleArea {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String[] sideOne = scanner.nextLine().split(" ");
String[] sideTwo = scanner.nextLine().split(" ");
String[] sideThree = scanner.nextLine().split(" ");
int aX = Integer.parseInt(sideOne[0]);
int aY = Integer.parseInt(sideOne[1]);
int bX = Integer.parseInt(sideTwo[0]);
int bY = Integer.parseInt(sideTwo[1]);
int cX = Integer.parseInt(sideThree[0]);
int cY = Integer.parseInt(sideThree[1]);
//CHECK IF CORRECT // System.out.printf("%d %d %d %d %d %d",aX,aY,bX,bY,cX,cY);
//USING THE FORULA FROM: mathopenref.com/coordtrianglearea.html
//WHICH IS: |((aX*(bY-cY) +bX*(cY-aY)+cX*(aY-bY)))/2|
int areaTriangle = ((aX * (bY - cY) + bX * (cY - aY) + cX * (aY - bY))) / 2;
System.out.println("The area of the triangle is: " + Math.abs(areaTriangle));
}
}