Question

The following code computes the radius of a circle. Using static methods from the Math class complete the method that computes the radius of a circle using the formula  r²=(x-h)² +(y-k)^{2 ,} given the (x,y) coordinates of one point on its circumference and the (h,k) coordinates of its center.

public class Circle {
   public static void main(String[] C)
   {
       double x1 =14.25;
       double y1 =13.68;
       double xCenter = 25.678;
       double yCenter = 10.32547;
       System.out.println("The first given points of your circle is ("+x1+", "+y1+")");
       System.out.println("The center points of your circle is ("+xCenter+", "+yCenter+")");
       double radius = radius(x1,y1,xCenter,yCenter);
       System.out.println("The radio of your circunferent is "+ radius);
      
       //Use a method to find the integer part of the radio.
       double radiusfloor = Math.floor(radius);
      
       System.out.println("The floor of the radius of your circunference is "+ radiusfloor);
   }
  
   public static double radius(double x,double y,double cx, double cy)
   {
       double radius = 0.0;  
       // write the expression to compute radius using the static methods pow() and sqrt() provided by Math class.
       return radius;
   }

}

Here is the JUnit Test:

import static org.junit.Assert.*;
import org.junit.Test;

public class CircleTest {

        @Test
        public void testRadius() {
                double epsilon = 1e-10;
                assertEquals("Circle.radius returned incorrect result", 0.0,Circle.radius(5,5,5,5), epsilon);
                assertEquals("Circle.radius returned incorrect result", 5, Circle.radius(3,4,0,0), epsilon);
                assertEquals("Circle.radius returned incorrect result", 13.19669493661197, Circle.radius(5.0285,1.055,5.24,14.25), epsilon);
                assertEquals("Circle.radius returned incorrect result", 63.97655820689325, Circle.radius(0,47,58,20), epsilon);
        }
        
}

Answer 1

package com.example.demo;
public class Circle {
   public static void main(String[] C) {
       double x1 = 14.25;
       double y1 = 13.68;
       double xCenter = 25.678;
       double yCenter = 10.32547;
       System.out.println("The first given points of your circle is (" + x1 + ", " + y1 + ")");
       System.out.println("The center points of your circle is (" + xCenter + ", " + yCenter + ")");
       double radius = radius(x1, y1, xCenter, yCenter);
       System.out.println("The radio of your circunferent is " + radius);

       // Use a method to find the integer part of the radio.
       double radiusfloor = Math.floor(radius);

       System.out.println("The floor of the radius of your circunference is " + radiusfloor);
   }

   public static double radius(double x, double y, double cx, double cy) {
       double radius = 0.0;
       // write the expression to compute radius using the static methods pow() and
       // sqrt() provided by Math class.
       double a = java.lang.Math.pow(x - cx, 2); // inbuilt pow method to caluclate (x-h)^2
       double b = java.lang.Math.pow(y - cy, 2); // inbuilt pow method to caluclate (y-k)^2
       radius = java.lang.Math.sqrt(a + b); // sqrt to find the value of radius r=sqrt(a+b);
       return radius; // returning the radius
   }

}

Please let me know in case you have any queries. Thanks !!!