Math.acos()
The Math.acos()
function returns the arccosine (in radians) of a number, that is
∀x ∈ [ − 1; 1], Math.acos
(``x``)
= arccos (x) = the unique y ∈ [0; π] such that cos (y) = x
Syntax
Math.acos(x)
Parameters
x
A number representing a cosine, where x
is between -1
and 1
.
Return value
The arccosine (angle in radians) of the given number if it's between -1
and 1
; otherwise, NaN
.
Description
The Math.acos()
method returns a numeric value between 0 and π radians for x
between -1 and 1. If the value of x
is outside this range, it returns NaN
.
Because acos()
is a static method of Math
, you always use it as Math.acos()
, rather than as a method of a Math
object you created (Math
is not a constructor).
Examples
Using Math.acos()
Math.acos(-2); // NaN
Math.acos(-1); // 3.141592653589793
Math.acos(0); // 1.5707963267948966
Math.acos(0.5); // 1.0471975511965979
Math.acos(1); // 0
Math.acos(2); // NaN
For values less than -1 or greater than 1, Math.acos()
returns NaN
.