Description
The asin() function calculates the arc sine value of the number provided as its only parameter, essentially reversing the operation of sine(). The return value is in radians—you should use the rad2deg() to convert radians to degrees.
$asin1 = asin(0.4346); $asin2 = asin(sin(80));
Syntax:
asin(float $num): float
Parameters
| Parameter | Description |
|---|---|
| num | The argument to process. |
Return Values
The arc sine of num in radians.
Examples
Example 1:
$sin = 0.75; echo "The arcsine of $sin is ", asin($sin);
Example 2:
<?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/>";
?> Example 3:
<?php
$arg = 1;
$val = asin($arg);
echo "asin(" . $arg . ") = " . $val . " radians.<br/>";
echo "Pi value = " . pi() . "<br/>";
echo "asin(" . $arg . ") = " . $val/pi()*180 . " degrees<br/>";
?>