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

Syntax
acos(x)

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))
?>

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Sureshbabu Harikrishnan
+91 9884320017