public class TestShapes { public static void main( String [] args) { Circle circ

Question

public class TestShapes {

   public static void main(String[] args) {

      Circle circle1 = new Circle(new Point(0.0, 0.0), 1.0);

      Circle circle2 = new Circle(new Point(0.0, 0.0), 2.0);

      Shape rectangle = new Rectangle(new Point(0.0, 0.0), new Point(1.0, 1.0));

      System.out.println("Area of circle 1 is: " + circle1.computeArea());

      System.out.println("Area of circle 2 is: " + circle2.computeArea());

      System.out.println("Area of rectangle is: " + rectangle.computeArea());

      return;

   }

}

Create a subclass titled ‘Triangle’ and is a concrete extension and has the following private attributes:

private Point vertex1;

private Point vertex2;

private Point vertex3;

and the following public methods:

boolean isRight(): returns true if the triangle is a right triangle, false otherwise

boolean isEquilateral(): returns true if the triangle is equilateral, false otherwise

Explanation / Answer

package assignment;

import java.awt.Point;

public class TestTriangleShape {
   public static void main(String[] args) {
       Triangle t1 = new Triangle(new Point(0,0),new Point(0,3),new Point(4,0));
       System.out.println(" Equilateraol : "+t1.isEquilateral()+ " Right Angle:"+ t1.isRight());
   }
}

class Triangle {
  
   private Point vertex1;

   private Point vertex2;

   private Point vertex3;
  
   // returns true if the triangle is a right triangle, false otherwise

   public Triangle(Point vertex1, Point vertex2, Point vertex3) {
       this.vertex1 = vertex1;
       this.vertex2 = vertex2;
       this.vertex3 = vertex3;
      
   }
   public boolean isRight() {
       //Pythagorean theorem: in right angle triangle, largest side should be equal to sqrt of (sum of squares of other sides)
       //find largest side
      
       double h = 0, a = 0, b = 0;
       double sides[] = getSides();
       if(sides[0] > sides [1]) {
           a = sides[1];
           if(sides[0] > sides [2]) {
               h = sides[0];
               b = sides[2];
           } else {
               h = sides[2];
               b = sides[0];
           }
          
       } else {
           a = sides[0];
           if(sides[1] > sides [2]) {
               h = sides[1];
               b = sides[2];
           } else {
               h = sides[3];
               b = sides[1];
           }
       }
      
       if(h == Math.sqrt(a * a + b* b))
           return true;
      
       return false;
   }
  
   //: returns true if the triangle is equilateral, false otherwise
   public boolean isEquilateral() {
       double sides[] = getSides();
       if(sides[0] == sides[1] && sides[1] == sides[2])
           return true;
       return false;
   }

   private double[] getSides() {
       double sides[] = new double[]{0,0,0};
       //side1.
       //distance between point p1(x1,y1) and point p2(x2,y2) is give by sqrt((x1-x2)^2+(y1-y2)^2)
       sides[0] = Math.sqrt(Math.pow(vertex1.getX()-vertex2.getX(), 2)
                            +Math.pow(vertex1.getY()-vertex2.getY(), 2));
      
       sides[1] = Math.sqrt(Math.pow(vertex3.getX()-vertex2.getX(), 2)
                +Math.pow(vertex3.getY()-vertex2.getY(), 2));
      
       sides[2] = Math.sqrt(Math.pow(vertex1.getX()-vertex3.getX(), 2)
                +Math.pow(vertex1.getY()-vertex3.getY(), 2));
       return sides;
   }
  
   public Point getVertex1() {
       return vertex1;
   }

   public void setVertex1(Point vertex1) {
       this.vertex1 = vertex1;
   }

   public Point getVertex2() {
       return vertex2;
   }

   public void setVertex2(Point vertex2) {
       this.vertex2 = vertex2;
   }

   public Point getVertex3() {
       return vertex3;
   }

   public void setVertex3(Point vertex3) {
       this.vertex3 = vertex3;
   }
  
  
}

--outut------

Equilateraol : false Right Angle:true

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