Question

Using Java

Create the class RightTriangle.

• Its constructor will require the lengths only of its two legs. It will then calculate the length of the third side (its “hypotenuse”) using the Pythagorean Theorem:

a² + b² = c².

• This class will have no instance variables itself, so it will need to set the appropriate variables in its parent class, Triangle.
• It will inherit equals from its parent class
• You also should enhance the String returned from the toString method of its parent class to identify this as a right triangle
• It will inherit getNumberOfSides, calculatePerimeter, and calculateArea from its parent.

You also should recalculate the hypotenuse every time one of the two legs changes. How would you do this?

In your main method,  create a right triangle with legs of length 3 and 4, use toString to print the lengths of all sides, the perimeter, and the area. Do the same using legs of length 5 and 12.

Triangle.java

public class Triangle extends Figure{

private double length1, length2, length3;
  
public Triangle(double len1, double len2, double len3)
{
this.length1 = len1;
this.length2 = len2;
this.length3 = len3;
}

public double getLength1() {
return length1;
}

public void setLength1(double length1) {
this.length1 = length1;
}

public double getLength2() {
return length2;
}

public void setLength2(double length2) {
this.length2 = length2;
}

public double getLength3() {
return length3;
}

public void setLength3(double length3) {
this.length3 = length3;
}
  
@Override
public int getNumberOfSides(){ return 3; }
  
@Override
public String toString()
{
return("Number of sides: " + getNumberOfSides() + ", Side1: " + String.format("%.2f", getLength1())
+ ", Side2: " + String.format("%.2f", getLength2())
+ ", Side3: " + String.format("%.2f", getLength3())
+ ", Area: " + String.format("%.2f", super.getArea())
+ ", Perimeter: " + String.format("%.2f", super.getPerimeter()));
}

@Override
public boolean equals(Object object) {
if(object instanceof Triangle)
{
return(getLength1() == ((Triangle) object).getLength1()
&& getLength2() == ((Triangle) object).getLength2()
&& getLength3() == ((Triangle) object).getLength3());
}
else
return false;
}

@Override
public void calculatePerimeter() {
setPerimeter(length1 + length2 + length3);
}

@Override
public void calculateArea() {
double p = super.getPerimeter() / 2;
double area = Math.sqrt(p * (p - length1) * (p - length2) * (p - length3));
super.setArea(area);
}
}

Answer 1

Thanks for the question,

Here is the implemented class - RightTriangle that inherits from Triangle class.

I have provided detailed comments so that you can follow the code precisely. The right triangle contains also the main test method that demonstrates the below two points -

create a right triangle with legs of length 3 and 4, use toString to print the lengths of all sides, the perimeter, and the area. Do the same using legs of length 5 and 12.

Please note : The question didnt had the Figure parent class which the Triangle class extends. So incase there is any error please do comment the errror you are getting so that I can change the code accordngly. But should not be the case.

===========================================================================

public class RightTriangle extends Triangle {


    public RightTriangle(double sideOne, double sideTwo) {

        super(sideOne, sideTwo, 0);

        setLength3(getHypotenuse());
    }


    // calculate length3 which is the Hypotenuse
    private double getHypotenuse() {
        // length3^2 = length1^2 + length2^2
        return Math.sqrt(getLength1() * getLength1() + getLength2() * getLength2());
    }



    // You also should recalculate the hypotenuse every time one of the two legs changes.
    @Override
    public void setLength1(double length1) {
        super.setLength1(length1);
        // everytime length 1 or length 2 changes we call getHypotenuse() method
        // and set the length of hypotenuse to that
        setLength3(getHypotenuse());
    }


    @Override
    public void setLength2(double length2) {
        super.setLength2(length2);
        // everytime length 1 or length 2 changes we call getHypotenuse() method
        // and set the length of hypotenuse to that
        setLength3(getHypotenuse());
    }

    @Override
    public String toString() {
        return super.toString();
    }

   public static void main(String[] args) {

       
        RightTriangle rightTriangle = new RightTriangle(3,4);
        // length3 should be 5
        System.out.println(rightTriangle);
       
        // set length1 to 5
        rightTriangle.setLength1(5);
        // set length2 to 12
        rightTriangle.setLength2(12);
        // length3 should be 13
        System.out.println(rightTriangle);
    }


}

=========================================================

thanks a lot !