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PHP cos() Function
Definition and Usage
The cos() function returns the cosine ratio of given angle in radians. In trigonometry, cosine of an angle is defined as ratio of lengths of adjacent side and hypotenuse.
cos(x) = adjacent/hypotenuse
If x=90 degree, cos(x) = 0.
This function returns a float value.
Syntax
cos ( float $arg ) : float
Parameters
| Sr.No | Parameter & Description |
|---|---|
| 1 | arg A floating point value that represents angle in radians |
Return Values
PHP cos() function returns cosine ratio of given parameter.
PHP Version
This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x.
Example
Following example calculates cos(pi/2) and returns 6.1232339957368E-17 (very close to 0). Cosine ratio of 90 deg is 0 −
<?php
$arg=M_PI_2;//represents pi/2 i.e. 90 deg.
$val=cos($arg);
echo "cos(" . $arg . ") = " . $val;
?>Output
This will produce following result −
cos(1.5707963267949) = 6.1232339957368E-17
Example
Following example uses deg2rad() function to convert degrees to radians and then uses cos(60). Result is 0.5 −
<?php
$arg=deg2rad(60);
$val=cos($arg);
echo "cos(" . $arg . ") = " . $val;
?>Output
This will produce following result −
cos(1.0471975511966) = 0.5
Example
Let's check find out cos(0). It returns 1 −
<?php
$arg=0;
$val=cos($arg);
echo "cos(" . $arg . ") = " . $val;
?>Output
This will produce following result −
cos(0) = 1
Example
Following example computes cos(pi) and returns -1
<?php
$arg=M_PI;
$val=cos($arg);
echo "cos(" . $arg . ") = " . $val;
?>Output
This will produce following result −
cos(3.1415926535898) = -1
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