acos
(PHP 4, PHP 5)
acos — Arc cosine
Description
float acos
( float
$arg
)
Returns the arc cosine of arg in radians.
acos() is the complementary function of
cos(), which means that
a==cos(acos(a)) for every value of a that is within
acos()' range.
Parameters
-
arg -
The argument to process
Return Values
The arc cosine of arg in radians.
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Коментарии
Parameter:
$num: A float value between -1 and 1. (Outside this range will return NAN)
Returns:
The arc cosine of the number in radians.
NAN (Not A Number) if the input is outside [-1, 1].
<?php
$cosValue = 0.5;
$angle = acos($cosValue); // returns angle in radians
echo $angle; // 1.0471975512 (which is ~60 degrees)
echo rad2deg($angle); // Convert to degrees: ~60
?>