HW5.19

 public class MyTriangle
 {
     public static boolean isValid(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(double side1, double side2, double side3)
     {
         double s = (side1 + side2 + side3) / 2;
         double areaSquare = s * (s - side1) * (s - side2) * (s -side3);
         double areaSqrt = Math.sqrt(areaSquare);
         return areaSqrt;
     }
 }

 import java.util.Scanner;

 public class TestMyTriangle
 {
     public static void main(String[] args)
     {
         Scanner input = new Scanner(System.in);

         System.out.print("Enter three sides: ");
         double s1 = input.nextDouble();
         double s2 = input.nextDouble();
         double s3 = input.nextDouble();

         input.close();

         System.out.println(MyTriangle.isValid(s1, s2, s3));
         System.out.println(MyTriangle.area(s1, s2, s3));
     }
 }