asin

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

asin — 反正弦

说明

asin ( float $arg ) : float

返回 arg 的反正弦值，单位是弧度。asin() 是 sin() 的反函数，它的意思是在 asin() 范围里的每个值都是 a==sin(asin(a)) 。

参数

arg: 待处理的参数

返回值

arg 的反正弦弧度。

参见

sin() - 正弦
asinh() - 反双曲正弦
acos() - 反余弦
atan() - 反正切

User Contributed Notes

rahmatjon at gmail dot com 16-Jan-2021 03:17


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/>";

?>