acos() function in PHP

The acos() function returns the arc cosine of a number. It specifies a number in the range -1 to 1. Returns NaN, if num is not in the range -1 to 1.

Syntax

acos(num)

Parameters

• num − The number for which you want to return the arc cosine. A number in range -1 to 1.

Return

The acos() function returns the arc cosine of the specified number.

Return

s NaN, if number is not in the range -1 to 1.

Example

<?php
   echo(acos(0.50) . "<br>");
   echo(acos(-0.90) . "<br>");
?>

Output

1.0471975511966<br>2.6905658417935<br>

Let us see another example −

Example

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

Output

1.5707963267949<br>0<br>3.1415926535898<br>NAN<br>