---
title: Math.asin()
slug: Web/JavaScript/Reference/Global_Objects/Math/asin
translation_of: Web/JavaScript/Reference/Global_Objects/Math/asin
original_slug: Web/JavaScript/Referencia/Objetos_globales/Math/asin
---
<div>{{JSRef}}</div>

<p>La Funcion <strong><code>Math.asin()</code></strong> retorna El arco seno (en radianes) de un número, eso es.</p>

<p><math display="block"><semantics><mrow><mo>∀</mo><mi>x</mi><mo>∊</mo><mo stretchy="false">[</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>;</mo><mn>1</mn><mo stretchy="false">]</mo><mo>,</mo><mspace width="thickmathspace"></mspace><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.asin</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mo lspace="0em" rspace="0em">arcsin</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo><mo>=</mo><mtext> the unique </mtext><mspace width="thickmathspace"></mspace><mi>y</mi><mo>∊</mo><mrow><mo>[</mo><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac><mo>;</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><mo>]</mo></mrow><mspace width="thinmathspace"></mspace><mtext>such that</mtext><mspace width="thickmathspace"></mspace><mo lspace="0em" rspace="0em">sin</mo><mo stretchy="false">(</mo><mi>y</mi><mo stretchy="false">)</mo><mo>=</mo><mi>x</mi></mrow><annotation encoding="TeX">\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</annotation></semantics></math></p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox"><code>Math.asin(<var>x</var>)</code></pre>

<h3 id="Parametros">Parametros</h3>

<dl>
 <dt><code>x</code></dt>
 <dd>Un Numero.</dd>
</dl>

<h3 id="Return_value">Return value</h3>

<p>The arcsine (in radians) of the given number if it's between <strong>-1</strong> and <strong>1</strong>; otherwise, {{jsxref("NaN")}}.</p>

<h2 id="Descripcion">Descripcion</h2>

<p>The <code>Math.asin()</code> method returns a numeric value between <math><semantics><mrow><mo>-</mo><mfrac><mi>π</mi><mn>2</mn></mfrac></mrow><annotation encoding="TeX">-\frac{\pi}{2}</annotation></semantics></math> and <math><semantics><mfrac><mi>π</mi><mn>2</mn></mfrac><annotation encoding="TeX">\frac{\pi}{2}</annotation></semantics></math> radians for <code>x</code> between -1 and 1. If the value of <code>x</code> is outside this range, it returns {{jsxref("NaN")}}.</p>

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

<h2 id="Ejemplos">Ejemplos</h2>

<h3 id="Usando_Math.asin()">Usando <code>Math.asin()</code></h3>

<pre class="brush: js">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
</pre>

<p>For values less than -1 or greater than 1, <code>Math.asin()</code> returns {{jsxref("NaN")}}.</p>

<h2 id="Espesificaciones">Espesificaciones</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Espesificacion</th>
   <th scope="col">Estado</th>
   <th scope="col">Comentario</th>
  </tr>
  <tr>
   <td>{{SpecName('ES1')}}</td>
   <td>{{Spec2('ES1')}}</td>
   <td>Initial definition. Implemented in JavaScript 1.0.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-15.8.2.3', 'Math.asin')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-math.asin', 'Math.asin')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-math.asin', 'Math.asin')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="Compatibilidad_con_Navegadores">Compatibilidad con Navegadores</h2>

{{Compat("javascript.builtins.Math.asin")}}

<h2 id="Ver_Mas">Ver Mas</h2>

<ul>
 <li>{{jsxref("Math.acos()")}}</li>
 <li>{{jsxref("Math.atan()")}}</li>
 <li>{{jsxref("Math.atan2()")}}</li>
 <li>{{jsxref("Math.cos()")}}</li>
 <li>{{jsxref("Math.sin()")}}</li>
 <li>{{jsxref("Math.tan()")}}</li>
</ul>