update: adds ASIN documentation page

docs/src/functions/math-and-trigonometry.md

@@ -18,7 +18,7 @@ You can track the progress in this [GitHub issue](https://github.com/ironcalc/Ir
 | ACOTH           | <Badge type="info" text="Not implemented yet" /> | –             |
 | AGGREGATE       | <Badge type="info" text="Not implemented yet" /> | –             |
 | ARABIC          | <Badge type="info" text="Not implemented yet" /> | –             |
-| ASIN            | <Badge type="tip" text="Available" />          | –             |
+| ASIN            | <Badge type="tip" text="Available" />          | [ASIN](math_and_trigonometry/asin) |
 | ASINH           | <Badge type="tip" text="Available" />          | –             |
 | ATAN            | <Badge type="tip" text="Available" />          | –             |
 | ATAN2           | <Badge type="tip" text="Available" />          | –             |

docs/src/functions/math_and_trigonometry/asin.md

@@ -4,8 +4,37 @@ outline: deep
 lang: en-US
 ---
 
-# ASIN
+# ASIN function
 
-::: warning
+## Overview
-🚧 This function is implemented but currently lacks detailed documentation. For guidance, you may refer to the equivalent functionality in [Microsoft Excel documentation](https://support.microsoft.com/en-us/office/excel-functions-by-category-5f91f4e9-7b42-46d2-9bd1-63f26a86c0eb).
+ASIN is a function of the Math and Trigonometry category that calculates the inverse sine (arcsine) of a number in the range [-1 to +1], returning an angle in the range [-$\pi$/2 to +$\pi$/2], expressed in radians.
-:::
+## Usage
+### Syntax
+**ASIN(<span title="Number" style="color:#1E88E5">number</span>) => <span title="Number" style="color:#1E88E5">asin</span>**
+### Argument descriptions
+* *number* ([number](/features/value-types#numbers), required). The number whose arcsine is to be calculated, in the range [-1 to +1]. 
+
+### Additional guidance
+None.
+### Returned value
+ASIN returns a number in radians in the range [-$\pi$/2 to +$\pi$/2] that is the angle whose sine is the specified number.
+### Error conditions
+* In common with many other IronCalc functions, ASIN propagates errors that are found in its argument.
+* If no argument, or more than one argument, is supplied, then ASIN returns the [`#ERROR!`](/features/error-types.md#error) error.
+* If the value of the *number* argument is not (or cannot be converted to) a [number](/features/value-types#numbers), then ASIN returns the [`#VALUE!`](/features/error-types.md#value) error.
+* If the value of the *number* argument lies outside the range [-1 to +1], then ASIN returns the [`#NUM!`](/features/error-types.md#num) error.
+* For some argument values, ASIN may return a [`#DIV/0!`](/features/error-types.md#div-0) error.
+<!--@include: ../markdown-snippets/error-type-details.txt-->
+## Details
+* The ASIN function utilizes the *asin()* method provided by the [Rust Standard Library](https://doc.rust-lang.org/std/).
+* The figure below illustrates the output of the ASIN function for angles $x$ in the range -1 to +1 radians.
+<center><img src="/functions/images/arcsine-curve.png" width="350" alt="Graph showing sin(x) for x between -2π and +2π."></center>
+
+## Examples
+[See some examples in IronCalc](https://app.ironcalc.com/?example=asin).
+
+## Links
+* For more information about inverse trigonometric functions, visit Wikipedia's [Inverse trigonometric functions](https://en.wikipedia.org/wiki/Inverse_trigonometric_functions) page.
+* See also IronCalc's [SIN](/functions/math_and_trigonometry/sin), [COS](/functions/math_and_trigonometry/cos) and [TAN](/functions/math_and_trigonometry/tan) functions.
+* Visit Microsoft Excel's [ASIN function](https://support.microsoft.com/en-us/office/asin-function-81fb95e5-6d6f-48c4-bc45-58f955c6d347) page.
+* Both [Google Sheets](https://support.google.com/docs/answer/3093464) and [LibreOffice Calc](https://wiki.documentfoundation.org/Documentation/Calc_Functions/ASIN) provide versions of the ASIN function.