# ACos

Returns the arccosine of a number in radians. The arccosine is the angle whose cosine is number.

See also Cos, Sin, ASin, Tan, and Pi.

### Syntax

    ACos(number)

##### number

Cosine of the angle that is to be calculated. This value must be between -1 and 1, inclusive.

### Usage

The range of the result is 0 to .

To convert degrees to radians, multiply degrees by /180. To convert radians to degrees, multiply radians by 180/.

### Examples

    <!--- This example shows how to use ACos --->

    <HTML>

    <HEAD>
    <TITLE>ACos Example</TITLE>
    </HEAD>

    <BODY BGCOLOR=silver>

    <H3>ACos Example</H3>

    <!--- output its arccosine value --->
    <CFIF IsDefined("FORM.CosNum")>
        <CFIF IsNumeric(FORM.CosNum)>
            <CFIF FORM.CosNum LESS THAN OR EQUAL TO 1>
                <CFIF FORM.CosNum GREATER THAN OR EQUAL TO -1>
                    ACos(<CFOUTPUT>#FORM.CosNum#</CFOUTPUT>) =
    <CFOUTPUT>#ACos(FORM.cosNum)# Radians</CFOUTPUT>
                    <BR>
                    or
                    <BR>
                    ACos(<CFOUTPUT>#FORM.CosNum#</CFOUTPUT>) =
    <CFOUTPUT>#Evaluate(ACos(FORM.cosNum) * 180/PI())# Degrees</CFOUTPUT>
                <CFELSE>
    <!--- if it is empty, output an error message --->
                <H4>Please enter a number between -1 and 1</H4>
                </CFIF>
            <CFELSE>
    <!--- if it is empty, output an error message --->
            <H4>Please enter a number between -1 and 1</H4>
            </CFIF>
        </CFIF>
    </CFIF>

    <FORM ACTION="acos.cfm" METHOD="POST">
    <P>Type in a number to get its arccosine in Radians and Degrees.
    <BR><INPUT TYPE="Text" NAME="cosNum" size="25">

    <P><INPUT TYPE="Submit" NAME=""> <INPUT TYPE="RESET">

    </FORM>

    </BODY>

    </HTML>