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PHP Exercises: Test whether AB and CD are orthogonal or not

PHP: Exercise-68 with Solution

There are four different points on a plane, P(xp,yp), Q(xq, yq), R(xr, yr) and S(xs, ys). Write a PHP program to test whether AB and CD are orthogonal or not.
xp,yp, xq, yq, xr, yr, xs and ys are -100 to 100 respectively and each value can be up to 5 digits after the decimal point It is given as a real number including the number of.

Sample Solution: -

PHP Code:

<?php
define('EPS', 1e-8);
    $a = fscanf(STDIN, '%f %f %f %f %f %f %f %f');
    $line = array();
    $line[] = $a[1] - $a[3] === 0.0 ? INF : ($a[0] - $a[2]) / ($a[1] - $a[3]);
    $line[] = $a[5] - $a[7] === 0.0 ? INF : ($a[4] - $a[6]) / ($a[5] - $a[7]);
    if (max($line) === INF && min($line) === 0 || abs($line[0] * $line[1] + 1.0) < EPS) {
        echo 'Orthogonal';
    } else {
        echo 'Not orthogonal';
    }
    echo PHP_EOL;
?>

Sample Input:
3.5 4.5 2.5 -1.5 3.5 1.0 0.0 4.5

Sample Output: 

Not orthogonal

Flowchart:

Flowchart: Test whether AB and CD are orthogonal or not.

PHP Code Editor:

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PHP: Tips of the Day

Returns all elements in an array except for the first one

Example:

<?php
function tips_tail($items)
{
  return count($items) > 1 ? array_slice($items, 1) : $items;
}

print_r(tips_tail([1, 5, 7]));
?>

Output:

Array
(
    [0] => 5
    [1] => 7
)