# PHP tan() Function

## Definition and Usage

The tan() function returns the tangent ratio of given angle in radians. In trigonometry, tangent of an angle is defined as ratio of lengths of opposite side and adjacent side.

tangent of an angle is also defined as ratio of its sine and cosine

tan(x) = sin(x)/cos(x)

If x=45 degree, tan(x) = 1 as in a right angled traingle, opposite and adjacent sides are qual.

This function returns a float value.

tan ( float $arg ) : float ## Parameters Sr.NoParameter & Description 1arg A floating point value that represents angle in radians ## Return Values PHP tan() function returns tangent ratio of given parameter. ## PHP Version This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x. ## Example Live Demo Following example calculates tan(pi/2) and returns 1.6331239353195E+16 (very large number). tngent ratio of 90 deg is infinity − <?php$arg=M_PI/2; //90 degree
$val=tan($arg);
echo "tan(" . $arg . ") = " .$val;
?>

## Output

This will produce following result −

tan(1.5707963267949) = 1.6331239353195E+16

## Example

Live Demo

Following example uses deg2rad() function to convert degrees to radians and then computes tan(60). Result is 1.7320508075689 which is sqrt(3) −

<?php
$arg=deg2rad(60);$val=tan($arg); echo "tan(" .$arg . ") = " . $val; ?> ## Output This will produce following result − tan(1.0471975511966) = 1.7320508075689 ## Example Live Demo Let's check find out tan(45) degrees. It returns 1 − <?php$arg=M_PI/4; //45 deg
$val=tan($arg);
echo "tan(" . $arg . ") = " .$val;
?>

## Output

This will produce following result −

tan(0.78539816339745) = 1

## Example

Live Demo

Following example computes tan(0) and returns 0

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

## Output

This will produce following result −

tan(0) = 0