note 79607 deleted from function.acos by googleguy
| From: | googleguy@php.net | Date: | Tue, 22 Oct 2013 06:47:39 +0000 |
| Subject: | note 79607 deleted from function.acos by googleguy | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-196644@lists.php.net to get a copy of this message | ||
Note Submitter: anthony at interiorgoodsdirect dot com
----
To calculate an angle from a triangle's sides.
Use the 'law of cosines' :
<?php
// a²+b²-c²
// cosC = --------
// 2ab
function calculateAngle($c,$a,$b)
{
$angleInRadians=acos((pow($a,2) + pow($b,2) - pow($c,2)) / (2 * $a * $b));
return rad2deg($angleInRadians);
}
?>
$a, $b, $c are the triangle sides.
The function returns the angle opposite side c, in degrees.