The "rad2deg()" function converts the radians number to the equivalent number in degrees.

    rad2deg(x)

In the above syntax "x" is the radian number to be converted to degrees.

    <?php
    $n =3.14;
    $degree = rad2deg($n);
    print "The value of $n in degrees is $degree";
    ?>

    The value of 3.14 in degrees is 179.908747671 

In the above example the value of "M_PI=3.14159265359" is equivalent to 180 degree.