asin()

Baseline 2023

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.

The asin() CSS function is a trigonometric function that returns the inverse sine of a number between -1 and 1. The function contains a single calculation that returns the number of radians representing an between -90deg and 90deg.

Syntax

css

/* Single  values */
transform: rotate(asin(-0.2));
transform: rotate(asin(2 * 0.125));

/* Other values */
transform: rotate(asin(pi / 5));
transform: rotate(asin(e / 3));

Parameters

The asin(number) function accepts only one value as its parameter.

number: A calculation which resolves to a between -1 and 1.

Return value

The inverse sine of an number will always return an between -90deg and 90deg.

If number is less than -1 or greater than 1, the result is NaN.
If number is 0⁻, the result is 0⁻.

Formal syntax

 = 
  asin(  )  

 = 
   [ [ '+' | '-' ]  ]*  

 = 
   [ [ '*' | / ]  ]*  

 = 
          |
       |
      |
    |
  (  )  

 = 
  e          |
  pi         |
  infinity   |
  -infinity  |
  NaN

Examples

Rotate elements

The asin() function can be used to rotate elements as it return an .

HTML

html

CSS

body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 50px;
}

css

div.box {
  width: 100px;
  height: 100px;
  background: linear-gradient(orange, red);
}
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));
}

Result

Specifications

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