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---
title: Math.cos()
slug: Web/JavaScript/Reference/Global_Objects/Math/cos
translation_of: Web/JavaScript/Reference/Global_Objects/Math/cos
---
<div>
{{JSRef("Global_Objects", "Math")}}</div>
<h2 id="Summary" name="Summary">概述</h2>
<p><code><strong>Math.cos()</strong></code> 函数返回一个数值的余弦值。</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox">Math.cos(<em>x</em>)</pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
<dt>
<code>x</code></dt>
<dd>
一个以弧度为单位的数值。</dd>
</dl>
<h2 id="Description" name="Description">描述</h2>
<p><code>cos</code> 方法返回一个 -1 到 1 之间的数值，表示角度（单位：弧度）的余弦值。</p>
<p>由于 <code>cos</code> 是 <code>Math</code> 的静态方法，所以应该像这样使用：<code>Math.cos()</code>，而不是作为你创建的 <code>Math</code> 实例的方法。</p>
<h2 id="Examples" name="Examples">示例</h2>
<h3 id="Example:_Using_Math.cos" name="Example:_Using_Math.cos">例子：使用 <code>Math.cos</code></h3>
<pre class="brush:js">Math.cos(0); // 1
Math.cos(1); // 0.5403023058681398
Math.cos(Math.PI); // -1
Math.cos(2 * Math.PI); // 1
</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">规范版本</th>
<th scope="col">规范状态</th>
<th scope="col">注解</th>
</tr>
<tr>
<td>ECMAScript 1st Edition. Implemented in JavaScript 1.0</td>
<td>Standard</td>
<td>Initial definition.</td>
</tr>
<tr>
<td>{{SpecName('ES5.1', '#sec-15.8.2.7', 'Math.cos')}}</td>
<td>{{Spec2('ES5.1')}}</td>
<td> </td>
</tr>
<tr>
<td>{{SpecName('ES6', '#sec-math.cos', 'Math.cos')}}</td>
<td>{{Spec2('ES6')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<p>{{ CompatibilityTable() }}</p>
<div id="compat-desktop">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Chrome</th>
<th>Firefox (Gecko)</th>
<th>Internet Explorer</th>
<th>Opera</th>
<th>Safari</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
</tr>
</tbody>
</table>
</div>
<div id="compat-mobile">
<table class="compat-table">
<tbody>
<tr>
<th>Feature</th>
<th>Android</th>
<th>Chrome for Android</th>
<th>Firefox Mobile (Gecko)</th>
<th>IE Mobile</th>
<th>Opera Mobile</th>
<th>Safari Mobile</th>
</tr>
<tr>
<td>Basic support</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
<td>{{ CompatVersionUnknown() }}</td>
</tr>
</tbody>
</table>
</div>
<h2 id="See_also" name="See_also">相关链接</h2>
<ul>
<li>The {{jsxref("Global_Objects/Math", "Math")}} object it belongs to.</li>
</ul>
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