PHP Functions Essential Reference

acos

float acos(float float) 

Returns the calculated arccosine of the given argument.

Returns:

Arccosine of a value

Description:

acos() calculates the arccosine of a value.

Version:

PHP 3, PHP 4

See also:

asin() 
atan() 
atan2() 
cos() 
sin() 
tan() 

Example:

Calculate the arccosine of a value

$cos = 0.5; echo "The arccosine of $cos is ", acos($cos);