PHP acos() Function
Example
Return the arc cosine of different numbers:
<?php
echo(acos(0.64) . "<br>");
echo(acos(-0.4) . "<br>");
echo(acos(0) . "<br>");
echo(acos(-1) . "<br>");
echo(acos(1) . "<br>");
echo(acos(2));
?>
Try it Yourself »
Definition and Usage
The acos() function returns the arc cosine of a number.
Tip: acos(-1) returns the value of Pi.
Syntax
acos(number);
Parameter Values
| Parameter | Description |
|---|---|
| number | Required. Specifies a number in range -1 to 1 |
Technical Details
| Return Value: | The arc cosine of a number. Returns NAN if number is not in the range -1 to 1 |
|---|---|
| Return Type: | Float |
| PHP Version: | 4+ |
❮ PHP Math Reference
