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PHP acos() Function

Complete PHP Math Reference

Definition and Usage

The acos() function returns the arccosine of a number as a numeric value value between 0 and PI radians.

Syntax

acos(x)

Parameter	Description
x	Required. Must be a numeric value in the range -1 to 1

Tips and Notes

Note: If the parameter x is outside the range -1 to 1, the browser will return -1.#IND.

Note: -1 will return the value of PI.

Example

In this example we will get the arccosine of different numbers:

<?php
echo(acos(0.64) . "<br />");
echo(acos(0) . "<br />");
echo(acos(-1) . "<br />");
echo(acos(1) . "<br />");
echo(acos(2))
?>

The output of the code above will be:

0.876298061168
1.57079632679
3.14159265359
0
-1.#IND