Definition and Usage

Most trigonometric functions like sin, cos, tan etc require angle argument in radians. The deg2rad() function proves useful in conversion of degrees to radians.

This function returns a float number such that number=deg2rad(x) where is angle in degrees. angle in radian = angle in deg *180/pi

deg2rad ( float $number ) : float Parameters Sr.NoParameter & Description 1number A float number reprsenting angle in degrees Return Values PHP deg2rad() function returns a float number that represents angle in radians. PHP Version This function is available in PHP versions 4.x, PHP 5.x as well as PHP 7.x. Example Live Demo Following example calculates radian equivalent of 30 degrees − <?php$arg=30;
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " .$val;
?>

Output

This will produce following result −

deg2rad(30) = 0.5235987755983

Example

Live Demo

Following example converts 180 deg in radians. We can confirm the result by comparing with value of M_PI. −

<?php
$arg=180;$val=deg2rad($arg); echo "deg2rad(" .$arg . ") = " . $val . ""; echo "pi in radians = ". M_PI; ?> Output This will produce following result − deg2rad(180) = 3.1415926535898 pi in radians = 3.1415926535898 Example Live Demo Non numeric argument produces error: − <?php$arg="Hello";
$val=deg2rad($arg);
echo "deg2rad(" . $arg . ") = " .$val;
?>

Output

This will produce following result −

PHP Warning: deg2rad() expects parameter 1 to be float, string given

Example

Live Demo

The argument number can be a binary, octal or hexadecimal decimal number. Following example converts 0x2d angle (equal to 45 degrees) to radians.

<?php
$arg=0x2d;$val=deg2rad($arg); echo "deg2rad(" .$arg . ") = " . \$val;
?>

Output

This will produce following result −

deg2rad(45) = 0.78539816339745