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PHP asin() Function

❮ PHP Math Reference

Example

Return the arc sine of different numbers:

<?php
echo(asin(0.64) . "<br>");
echo(asin(-0.4) . "<br>");
echo(asin(0) . "<br>");
echo(asin(-1) . "<br>");
echo(asin(1) . "<br>");
echo(asin(2));
?>
Run example »

Definition and Usage

The asin() function returns the arc sine of a number.

Tip: asin(1) returns the value of Pi/2.


Syntax

asin(number);

Parameter Description
number Required. Specifies a number in range -1 to 1

Technical Details

Return Value: The arc sine of a number. Returns NAN if number is not in the range -1 to 1
Return Type: Float
PHP Version: 4+

❮ PHP Math Reference