PHP cos() function

Definition and Usage

cos()The function returns the cosine ratio of a given angle in radians. In trigonometry, the cosine of an angle is defined as the ratio of the length of the adjacent side to the hypotenuse.

cos(x) = adjacent/hypotenuse

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

This function returns a floating point value.

Syntax

<strong>cos</strong> ( float $arg ) : float

Parameters

Sr.No	Parameters and description
1	arg Floating point value representing the angle in radians

Return value

The PHP cos() function returns the cosine ratio of the given parameters.

PHP Version

This function is available in PHP version 4.x, PHP 5.x and PHP 7.x.

Example

Real-time demonstration

The following example calculates cos(pi/2) and returns 6.1232339957368E-17 (very close to 0). The cosine ratio of 90 degrees 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 the following results-

cos(1.5707963267949) = 6.1232339957368E-17

Example

Live Demonstration

The following example uses the deg2rad() function to convert degrees to radians and then uses cos(60). The result is 0.5 -

<?php
   $arg=deg2rad(60);
   $val=cos($arg);
   echo "cos(" . $arg . ") = " . $val;
?>

Output

This will produce the following result-

cos(1.0471975511966) = 0.5

Example

Live Demo

Let's check it out cos(0). It returns 1 -

<?php
   $arg=0;
   $val=cos($arg);
   echo "cos(" . $arg . ") = " . $val;
?>

Output

This will produce the following result-

cos(0) = 1

Example

Live Demonstration

The following example calculates cos (pi) and returns -1

<?php
   $arg=M_PI;
   $val=cos($arg);
   echo "cos(" . $arg . ") = " . $val;
?>

output

This will produce the following result-

cos(3.1415926535898) = -1

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