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

X( degree ̊ )
X(Rad)
Y = Cosine(X)
180 ̊
π
-1
150 ̊
5π/6
-0.866025
135 ̊
3π/4
-0.707107
120 ̊
2π/3
-0.5
90 ̊
π/2
0
60 ̊
π/3
0.5
45 ̊
π/4
0.707107
30 ̊
π/6
0.866025
0 ̊
0
1
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