PHP Conference Nagoya 2025

asin

(PHP 4, PHP 5, PHP 7, PHP 8)

asinArc sine

Description

asin(float $num): float

Returns the arc sine of num in radians. asin() is the inverse function of sin(), which means that $num == sin(asin($num)) for every value of num that is in the domain of asin().

Parameters

num

The argument to process

Return Values

The arc sine of num in radians

See Also

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User Contributed Notes 1 note

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rahmatjon at gmail dot com
3 years ago
Hello!
Please put this example below the asin() function's description.
Thank you!

Example:
<?php
$arg
= 0.5;
$val = asin($arg);
echo
"asin(" . $arg . ") = " . $val . " radians.<br/>";
echo
"Pi value = " . pi() . "<br/>";
echo
"asin(" . $arg . ") = " . $val/pi()*180 . " degrees<br/>";

$arg = 1;
$val = asin($arg);
echo
"asin(" . $arg . ") = " . $val . " radians.<br/>";
echo
"Pi value = " . pi() . "<br/>";
echo
"asin(" . $arg . ") = " . $val/pi()*180 . " degrees<br/>";
?>
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