/JavaScript

# Math.asin

The Math.asin() function returns the arcsine (in radians) of a number, that is

$∀x∊[-1;1],Math.asin(x)=arcsin(x)= the unique y∊[-π2;π2]such thatsin(y)=x\forall x \in [{-1};1],\;\mathtt{\operatorname{Math.asin}(x)} = \arcsin(x) = \text{ the unique } \; y \in \left[-\frac{\pi}{2}; \frac{\pi}{2}\right] \, \text{such that} \; \sin(y) = x$

## Syntax

Math.asin(x)

### Parameters

x
A number.

### Return value

The arcsine (in radians) of the given number if it's between -1 and 1; otherwise, NaN.

## Description

The Math.asin() method returns a numeric value between $-\frac\left\{\pi\right\}\left\{2\right\}$ and $\frac\left\{\pi\right\}\left\{2\right\}$ radians for x between -1 and 1. If the value of x is outside this range, it returns NaN.

Because asin() is a static method of Math, you always use it as Math.asin(), rather than as a method of a Math object you created (Math is not a constructor).

## Examples

### Using Math.asin()

Math.asin(-2);  // NaN
Math.asin(-1);  // -1.5707963267948966 (-pi/2)
Math.asin(0);   // 0
Math.asin(0.5); // 0.5235987755982989
Math.asin(1);   // 1.5707963267948966 (pi/2)
Math.asin(2);   // NaN


For values less than -1 or greater than 1, Math.asin() returns NaN.

## Browser compatibilityUpdate compatibility data on GitHub

Desktop
Chrome Edge Firefox Internet Explorer Opera Safari
asin 1 12 1 3 3 1
Mobile
Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet
asin 1 18 4 10.1 1 1.0
Server
Node.js
asin 0.1.100

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