# How to Find Inverse of sine or Arc sine in Python using asine() Function

To find out the inverse of sine or arcsine in Python we use `math.asin()` function or Standard math Library. The inverse of sine is also called arcsine.

## `asin()` Function in Python

`math.asin()` function exists in Standard math Library of Python Programming Language. The purpose of this function is to calculate arcsine or the inverse of the sine of any given number within the range of -1 and 1.

## Python `asin()` Function Syntax

The syntax of `asin()` function in Python is
`math.asin( x )`

## Python `asin()` Function Parameters

`X` Any valid Python number (positive or negative within the range of -1 and 1). This parameter is required.
Note: if the `x` parameter is not a number or greater than 1, `asin()` function will return an `error`.

Python 2.x – Yes
Python 3.x – Yes

## Python `asin()` Function Return Value

`asin()` function will return a floating point number (a value of the inverse of sine in radians).

## Python `asin()` Function Example

```# import math library
import math

print (math.asin(-0.2))
print (math.asin(0.0))
print (math.asin(0.2))
print (math.asin(1))```

Output of Python `asin()` function:
```-0.2013579207903308 0.0 0.2013579207903308 1.5707963267948966```

Note that the unit of output is radian.