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 $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); ?>
Central coordinate(x,y) and radius of the circle: (1.000 1.000) 1.414
PHP Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
What is the difficulty level of this exercise?