# Asin()

Published Sep 6, 2023
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The `Asin()` function returns the inverse sine of a number.

## Syntax

``````result := math.Asin(number)
``````

The `Asin()` function takes one parameter, `number`, a type of `float64`, which must be within the range of `-1` and `1` (inclusive).

The `Asin()` function returns a number, the inverse sine (also known as arcsine) value of `number` as a `float64`. This returned value represents an angle in radians whose sine equals the `number`. If the value of `number` is:

• Zero (`0`), then it returns `0`
• Less than `-1`, then it returns `NAN` (Not a Number)
• Greater than `1`, then it returns `NAN`

Note: The `math` library must be imported first to use this function.

## Example

The following example first calculates the inverse sine of `num` and then prints out the result to the console:

```package main
import (  "fmt"  "math")
func main() {  num := 0.9
inverseSine := math.Asin(num)  fmt.Printf("The inverse sine of %f is %f\n", num, inverseSine)}
```

The output will be:

```The inverse sine of 0.900000 is 1.119770
```

## Codebyte Example

The following example is runnable and uses the `Asin()` function with two values: `1.1` and `0.0`.

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