PHP Exercises: Compute the radius and the central coordinate of a circle
PHP: Exercise-53 with Solution
Write a PHP program to compute the radius and the central coordinate (x, y) of a circle which is constructed by three given points on the plane surface.
Sample Solution: -
PHP Code:
<?php
$x1 = 0; $y1 = 0; $x2 = 2; $y2 = 0; $x3 = 2; $y3 = 2;
$a1 = 2 * ($x2 - $x1);
$b1 = 2 * ($y2 - $y1);
$c1 = $x1 * $x1 - $x2 * $x2 + $y1 *$y1 - $y2 * $y2;
$a2 = 2 * ($x3 - $x1);
$b2 = 2 * ($y3 - $y1);
$c2 = $x1 * $x1 - $x3 * $x3 + $y1 *$y1 - $y3 * $y3;
$x = ($b1 * $c2 - $b2 * $c1) / ($a1 * $b2 - $a2 * $b1);
$y = ($c1 * $a2 - $c2 * $a1) / ($a1 * $b2 - $a2 * $b1);
$r = sqrt(($x - $x1) * ($x - $x1) + ($y - $y1) * ($y - $y1));
printf("Central coordinate(x,y) and radius of the circle:\n");
printf("(%.3f %.3f) %.3f\n", $x, $y, $r);
?>
Sample Output:
Central coordinate(x,y) and radius of the circle: (1.000 1.000) 1.414
Flowchart:

PHP Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous: Write a PHP program to print the number of prime numbers which are less than or equal to a given integer.
Next: Write a PHP program to compute the sum of the digits of a number.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
PHP: Tips of the Day
Why shouldn't I use mysql_* functions in PHP?
The MySQL extension:
- Is not under active development
- Is officially deprecated as of PHP 5.5 (released June 2013).
- Has been removed entirely as of PHP 7.0 (released December 2015)
- This means that as of 31 Dec 2018 it does not exist in any supported version of PHP. If you are using a version of PHP which supports it, you are using a version which doesn't get security problems fixed.
- Lacks an OO interface
- Doesn't support:
- Non-blocking, asynchronous queries
- Prepared statements or parameterized queries
- Stored procedures
- Multiple Statements
- Transactions
- The "new" password authentication method (on by default in MySQL 5.6; required in 5.7)
- Any of the new functionality in MySQL 5.1 or later
Since it is deprecated, using it makes your code less future proof.
Lack of support for prepared statements is particularly important as they provide a clearer, less error-prone method of escaping and quoting external data than manually escaping it with a separate function call.
Ref : https://bit.ly/2BIIsF0
- New Content published on w3resource:
- HTML-CSS Practical: Exercises, Practice, Solution
- Java Regular Expression: Exercises, Practice, Solution
- Scala Programming Exercises, Practice, Solution
- Python Itertools exercises
- Python Numpy exercises
- Python GeoPy Package exercises
- Python Pandas exercises
- Python nltk exercises
- Python BeautifulSoup exercises
- Form Template
- Composer - PHP Package Manager
- PHPUnit - PHP Testing
- Laravel - PHP Framework
- Angular - JavaScript Framework
- Vue - JavaScript Framework
- Jest - JavaScript Testing Framework