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Math.acos() 함수는 입력한 숫자의 코사인 역함수 값을 반환한다. (반환값은 라디안 단위이다.) 즉,
x[-1;1],Math.acos(x)=arccos(x)= the unique y[0;π]such thatcos(y)=x\forall x \in [{-1};1],\;\mathtt{\operatorname{Math.acos}(x)} = \arccos(x) = \text{ the unique } \; y \in [0; \pi] \, \text{such that} \; \cos(y) = x




숫자 형식.

Return value

[-1, 1]의 숫자를 입력했을 때, 입력한 숫자의 코사인 역함수 값을 반환한다. 그 외의 숫자를 입력하면, NaN을 반환한다.


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).


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.


Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Math.acos' in that specification.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Math.acos' in that specification.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Math.acos' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

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