## Saturday, 20 August 2016

### Chapter 6 Exercise 19, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

*6.19 (The MyTriangle class) Create a class named MyTriangle that contains the following two methods:

/** Return true if the sum of any two sides is greater than the third side. */
public static boolean isValid( double side1, double side2, double side3)

/** Return the area of the triangle. */
public static double area( double side1, double side2, double side3)

Write a test program that reads three sides for a triangle and computes the area if the input is valid. Otherwise, it displays that the input is invalid. The formula for computing the area of a triangle is given in Programming Exercise 2.19.

import java.util.Scanner;

public class MyTriangle {

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

System.out.print("Enter three edges of the triangle:");
double side1 = input.nextDouble();
double side2 = input.nextDouble();
double side3 = input.nextDouble();

if (!isValid(side1, side2, side3)) {
System.out.print("The input is invalid");
System.exit(0);
}

System.out.print("The area of the triangle is  "
+ area(side1, side2, side3));

}

public static boolean isValid(double side1, double side2, double side3) {
return !(side1 > side2 + side3 || side2 > side1 + side3 || side3 > side1
+ side2);
}

public static double area(double side1, double side2, double side3) {
double s = (side1 + side2 + side3) / 2;
double area = Math.sqrt(s * (s - side1) * (s - side2) * (s - side3));

return area;
}
}