PHP cos()

PHP cos(x) function returns the cosine value of x. The principle values for x is [-∞,∞].

<?PHP
	echo cos(M_PI); //-1
	echo cos(M_PI/3); //0.5
?>

deg2rad() function can be used to convert degree to radian angle.

<?PHP
	echo cos(deg2rad(60));  //0.5
	echo cos(deg2rad(30));  //0.86602540378444
?>

Cosine y=cos(x) Graph