Math.acos()

The Math.acos() static method returns the inverse cosine (in radians) of a number. That is,

∀x∊[−1,1],𝙼𝚊𝚝𝚑.𝚊𝚌𝚘𝚜(𝚡)=arccos(x)=the unique y∊[0,π] such that cos(y)=xforall x in [{-1}, 1],;mathtt{operatorname{Math.acos}(x)} = arccos(x) = text{the unique } y in [0, pi] text{ such that } cos(y) = x

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).

Return value: The inverse cosine (angle in radians between 0 and π, inclusive) of x. If x is less than -1 or greater than 1, returns NaN.

Syntax example: Math.acos(x)