PHP cos() Function

The PHP cos() function returns trigonometric cosine of an angle (angle should be in radians). In special cases it returns the following:

If the argument is NAN or an infinity, then the result is NAN.

In the graph below, cos(x) vs x is plotted.

Syntax

cos(number)

Parameters

number Required. Specify the angle in radian.

Return Value

Returns the trigonometric cosine of an angle.

Example:

In the example below, cos() function is used to find out the trigonometric cosine of an angle.

<?php 
echo "cos(pi()/6) = ".cos(pi()/6)."\n";
echo "cos(pi()/4) = ".cos(pi()/4)."\n";
echo "cos(pi()/3) = ".cos(pi()/3)."\n"; 
echo "cos(deg2rad(45)) = ".cos(deg2rad(45))."\n";
echo "cos(M_PI/2) = ".cos(M_PI/2)."\n"; 
echo "cos(M_PI_4) = ".cos(M_PI_4)."\n";
echo "cos(NAN) = ".cos(NAN)."\n";
echo "cos(INF) = ".cos(INF)."\n";
?>

The output of the above code will be:

cos(pi()/6) = 0.86602540378444
cos(pi()/4) = 0.70710678118655
cos(pi()/3) = 0.5
cos(deg2rad(45)) = 0.70710678118655
cos(M_PI/2) = 6.1232339957368E-17
cos(M_PI_4) = 0.70710678118655
cos(NAN) = NAN
cos(INF) = NAN

❮ PHP Math Reference