# asin()

## Baseline2023

Newly available

Since March 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

CSS 函数 asin() 为三角函数，返回介于 -11 之间的数的反正弦值。此函数含有单个计算式，此式返回表示介于 -90deg90deg 之间的 <angle> 的弧度数。

## 语法

css
/* 单个 <number> 值 */
transform: rotate(asin(-0.2));
transform: rotate(asin(2 * 0.125));

/* 其他值 */
transform: rotate(asin(pi / 5));
transform: rotate(asin(e / 3));

### 参数

asin(number) 函数仅接受一值作为其参数。

number

### 返回值

number 的反正弦值总将返回介于 -90deg90deg 之间的 <angle>

• number 小于 -1 或大于 1，则结果为 NaN
• number0⁻，则结果为 0⁻

### 形式语法

<asin()> =
asin( <calc-sum> )

<calc-sum> =
<calc-product> [ [ '+' | '-' ] <calc-product> ]*

<calc-product> =
<calc-value> [ [ '*' | '/' ] <calc-value> ]*

<calc-value> =
<number> |
<dimension> |
<percentage> |
<calc-keyword> |
( <calc-sum> )

<calc-keyword> =
e |
pi |
infinity |
-infinity |
NaN

## 示例

### 旋转元素

#### HTML

html
<div class="box box-1"></div>
<div class="box box-2"></div>
<div class="box box-3"></div>
<div class="box box-4"></div>
<div class="box box-5"></div>

#### CSS

css
div.box {
width: 100px;
height: 100px;
}
div.box-1 {
transform: rotate(asin(1));
}
div.box-2 {
transform: rotate(asin(0.5));
}
div.box-3 {
transform: rotate(asin(0));
}
div.box-4 {
transform: rotate(asin(-0.5));
}
div.box-5 {
transform: rotate(asin(-1));
}

## 规范

Specification
CSS Values and Units Module Level 4
# trig-funcs

## 浏览器兼容性

BCD tables only load in the browser