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ASin

Last update:
May 18, 2026

Description

Determines the arcsine of a number. The arcsine is the angle whose sine is number.

Returns

The arcsine, in radians, of a number.

Category

Function syntax

ASin(number)

See also

SinCosACosTanAtnPi

Parameters

Parameter
Description
number
Sine of an angle. The value must be between -1 and 1, inclusive.

Usage

The range of the result is -p/2 to p/2 radians. To convert degrees to radians, multiply degrees by p/180. To convert radians to degrees, multiply radians by 180/p.

Example

<h3>ASin Example</h3> 
 <!--- Output its arcsine value. ---> 
 <cfif IsDefined("FORM.SinNum")> 
 <cfif IsNumeric(FORM.SinNum)> 
 <cfif FORM.SinNum LESS THAN OR EQUAL TO 1> 
 <cfif FORM.SinNum GREATER THAN OR EQUAL TO -1> 
 ASin(<cfoutput>#FORM.SinNum#</cfoutput>) = 
 <cfoutput>#ASin(FORM.sinNum)# Radians</cfoutput> 
 <br> or <br>ASin(<cfoutput>#FORM.SinNum#</cfoutput>) = 
 <cfoutput> 
 #ASin(FORM.sinNum) * 180/Pi()# Degrees 
 </cfoutput> 
 <cfelse> 
 <!--- If it is less than negative one, output an error message. ---> 
 <h4>Enter the sine of the angle to calculate, in degrees and radians. 
 The value must be between 1 and -1, inclusive.</h4> 
 </cfif> 
 <cfelse> 
 <!--- If it is greater than one, output an error message. ---> 
 <h4>Enter the sine of the angle to calculate, in degrees and radians. The 
 value must be between 1 and -1, inclusive.</h4> 
 </cfif> 
 <cfelse> 
 <!--- If it is empty, output an error message. ---> 
 <h4>Enter the sine of the angle to calculate, in degrees and radians. The 
 value must be between 1 and -1,inclusive.</h4> 
 </cfif> 
 </cfif> 
 <form action = "./evaltest.cfm" method="post"> 
 <p>Enter a number to get its arcsine in Radians and Degrees. 
 <br><input type = "Text" name = "SinNum" size = "25"> 
 <p><input type = "Submit" name = ""> <input type = "RESET"> 
 </form>

Example

<cfscript>
   number=0.5;
   writeOutput(asin(0.5));  // Returns 0.523598775598
</cfscript>

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