Excel ASIN Function calculates the arcsine of a given number, returning an angle in radians whose sine is the specified number. It is useful for solving problems related to trigonometry and geometry.

## Syntax

**ASIN(number)**

## Arguments

number | The sine of the angle you want to find. Must be between -1 and 1. |

## How to use

The ASIN function is quite straightforward to use. You provide a value for the ‘number’ argument, and it returns the arcsine of that number in radians.

Here’s a simple example:

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=ASIN(0.5) |

This formula will return the arcsine of 0.5, which is approximately 0.5236 radians or 30 degrees. It tells you that the sine of 0.5236 radians is 0.5.

Let’s say you have a right-angled triangle, and you know one of the non-right angles is 30 degrees, and you want to find the length of the side opposite that angle. You can use the ASIN function to calculate it.

First, convert the angle to radians using the RADIANS function:

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=RADIANS(30) |

This will give you 0.5236 radians. Now, you can use the SIN function to find the length of the opposite side:

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=SIN(RADIANS(30)) |

ASIN is the inverse of this operation. It takes the value 0.5 and gives you back the angle of 30 degrees or 0.5236 radians.

## Additional information

If you’re not familiar with the terms ‘radians’ or ‘sine,’ you can refer to trigonometry and geometry resources to understand these concepts better. Radians are a way to measure angles, and the sine of an angle is a trigonometric function that relates the angle to the length of the sides of a right-angled triangle.