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acos() - CSS | MDN
acos()
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2023.
The acos() CSS function is a trigonometric function that returns the inverse cosine of a number between -1 and 1. The function contains a single calculation that returns the number of radians representing an <angle> between 0deg and 180deg.
Syntax
css
/* Single <number> values */
transform: rotate(acos(-0.2));
transform: rotate(acos(2 * 0.125));
/* Other values */
transform: rotate(acos(pi / 5));
transform: rotate(acos(e / 3));
Parameters
The acos(number) function accepts only one value as its parameter.
Return value
The inverse cosine of an number will always return an <angle> between 0deg and 180deg.
- If
numberis less than-1or greater than1, the result isNaN. - If
numberis exactly1, the result is0.
Formal syntax
<acos()> =
acos( <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
Examples
Rotate elements
The acos() function can be used to rotate elements as it return an <angle>.
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
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(acos(1));
}
div.box-2 {
transform: rotate(acos(0.5));
}
div.box-3 {
transform: rotate(acos(0));
}
div.box-4 {
transform: rotate(acos(-0.5));
}
div.box-5 {
transform: rotate(acos(-1));
}
Result
Specifications
| Specification |
|---|
| CSS Values and Units Module Level 4 # trig-funcs |
Browser compatibility
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