# PHP cos() Function

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## 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.

If x=90 degree, cos(x) = 0.

This function returns a float value.

cos ( float $arg ) : float ## Parameters Sr.NoParameter & Description 1arg A floating point value that represents angle in radians ## Return Values PHP cos() function returns cosine ratio of given parameter. ## PHP Version This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x. ## Example Live Demo Following example calculates cos(pi/2) and returns 6.1232339957368E-17 (very close to 0). Cosine ratio of 90 deg is 0 − <?php$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

Live Demo

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 . ") = " . $val; ?> ## Output This will produce following result − cos(1.0471975511966) = 0.5 ## Example Live Demo Let's check find out cos(0). It returns 1 − <?php$arg=0;
$val=cos($arg);
echo "cos(" . $arg . ") = " .$val;
?>

## Output

This will produce following result −

cos(0) = 1

## Example

Live Demo

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
Updated on 29-Jun-2020 08:37:20