# Java: Compute the radius and the central coordinate of a circle

## Java Basic: Exercise-218 with Solution

Write a Java program to compute the radius and central coordinates (x, y) of a circle constructed from three given points on the plane surface.

Input:

x1,y1,x2,y2,x3,y3,xp,yp separated by a single space.

Sample Solution:

Java Code:

``````// Importing necessary classes for input/output operations
import java.io.IOException;

// Main class named "Main"
class Main {
// Main method with IOException in case of input error
public static void main(String[] args) throws IOException {
// Creating BufferedReader for efficient reading of input

// Prompting the user to input coordinates x1, y1, x2, y2, x3, y3 separated by a single space
System.out.println("Input x1, y1, x2, y2, x3, y3 separated by a single space:");

// Reading the input line and splitting it into an array of strings
String[] input = br.readLine().split(" ");

// Parsing the input strings into double values
double x1 = Double.parseDouble(input[0]);
double y1 = Double.parseDouble(input[1]);
double x2 = Double.parseDouble(input[2]);
double y2 = Double.parseDouble(input[3]);
double x3 = Double.parseDouble(input[4]);
double y3 = Double.parseDouble(input[5]);

// Calculating intermediate values for further computations
double A = x2 - x1;
double B = y2 - y1;
double p = (y2 * y2 - y1 * y1 + x2 * x2 - x1 * x1) / 2;
double C = x3 - x1;
double D = y3 - y1;
double q = (y3 * y3 - y1 * y1 + x3 * x3 - x1 * x1) / 2;

// Calculating the coordinates of the center (X, Y) and the radius (r) of the circle
double X = (D * p - B * q) / (A * D - B * C);
double Y = (A * q - C * p) / (A * D - B * C);

double r = Math.sqrt(Math.pow(X - x1, 2.0) + Math.pow(Y - y1, 2.0));

// Displaying the radius and the central coordinate of the circle
System.out.println("\nRadius and the central coordinate:");
System.out.printf("%.3f (%.3f %.3f)", r, X, Y);
}
}
```
```

Sample Output:

```Input x1, y1, x2, y2, x3, y3 separated by a single space:
5 6 4 8 7 9

Radius and the central coordinate:
1.821 (5.786 7.643)
```

Flowchart:

Java Code Editor:

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