# The Excel ASIN Function

Arcsine

The Arcsine is the inverse of the sine.

Therefore, for the simple right-angled triangle below, the arcsine of the opposite side, o, divided by the hypotenuse, h, is equal to the angle θ. I.e. for the triangle above, The Inverse trig. functions are discussed further on the Wikipedia Inverse Trigonometric Functions Page

## Function Description

The Excel ASIN function calculates the arcsine (i.e. the inverse sine) of a given number, and returns an angle, in radians, between -π/2 and π/2.

The syntax of the function is:

ASIN( number )

Where the number argument is the value, between -1 and +1, for which you want to calculate the arcsine.

If you want the angle returned by the Asin function to be expressed in degrees, you can convert it, using the Excel Degrees function:

An example of this is provided below.

## Excel Asin Function Examples

The following spreadsheet shows the Excel Asin Function, used to calculate the arcsine of four different values.

Formulas:
A
1=ASIN( -1 )
2=ASIN( 0 )
3=ASIN( 1 / SQRT(2) )
4=DEGREES( ASIN( 1 / SQRT(2) ) )
Results:
AB
1-1.570796327 - Result is -π/2 radians
20 - Result is 0 radians
30.785398163 - Result is π/4 radians
445 - Result is 45 degrees

Note that in cell A4, the Excel Degrees function is used to convert the calculated angle from radians to degrees.

For further information and examples of the Excel Asin function, see the Microsoft Office website.

## Asin Function Errors

If you get an error from the Excel Asin Function, this is likely to be one of the following:

Common Errors
 #NUM! - Occurs if the supplied number argument is not in the range -1 to +1. #VALUE! - Occurs if the supplied number argument is non-numeric.